Merging upstream version 127.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

61 files changed, 1964 insertions, 816 deletions

diff --git a/devtools/client/aboutdebugging/test/node/README.md b/devtools/client/aboutdebugging/test/node/README.md
index 58cbe55691..f6a37e2607 100644
--- a/devtools/client/aboutdebugging/test/node/README.md
+++ b/devtools/client/aboutdebugging/test/node/README.md
@@ -19,4 +19,4 @@ The tests run on try on linux64 platforms. The complete name of try job is `devt
 Adding the tests to a try push depends on the try selector you are using.
 - try fuzzy: look for the job named `source-test-node-devtools-tests`
 
-The configuration file for try can be found at `taskcluster/ci/source-test/node.yml`
+The configuration file for try can be found at `taskcluster/kinds/source-test/node.yml`
diff --git a/devtools/client/accessibility/test/node/README.md b/devtools/client/accessibility/test/node/README.md
index 4b40aacffe..574f886e94 100644
--- a/devtools/client/accessibility/test/node/README.md
+++ b/devtools/client/accessibility/test/node/README.md
@@ -19,4 +19,4 @@ The tests run on try on linux64 platforms. The complete name of try job is `devt
 Adding the tests to a try push depends on the try selector you are using.
 - try fuzzy: look for the job named `source-test-node-devtools-tests`
 
-The configuration file for try can be found at `taskcluster/ci/source-test/node.yml`
+The configuration file for try can be found at `taskcluster/kinds/source-test/node.yml`
diff --git a/devtools/client/bin/devtools-node-test-runner.js b/devtools/client/bin/devtools-node-test-runner.js
index 087664b957..3c08b6577f 100644
--- a/devtools/client/bin/devtools-node-test-runner.js
+++ b/devtools/client/bin/devtools-node-test-runner.js
@@ -10,7 +10,7 @@
  * This is a test runner dedicated to run DevTools node tests continuous integration
  * platforms. It will parse the logs to output errors compliant with treeherder tooling.
  *
- * See taskcluster/ci/source-test/node.yml for the definition of the task running those
+ * See taskcluster/kinds/source-test/node.yml for the definition of the task running those
  * tests on try.
  */
 
diff --git a/devtools/client/debugger/src/actions/context-menus/editor.js b/devtools/client/debugger/src/actions/context-menus/editor.js
index 4785c963cb..2b82628f1a 100644
--- a/devtools/client/debugger/src/actions/context-menus/editor.js
+++ b/devtools/client/debugger/src/actions/context-menus/editor.js
@@ -39,7 +39,7 @@ import { toggleBlackBox } from "../../actions/sources/blackbox";
 import { addExpression } from "../../actions/expressions";
 import { evaluateInConsole } from "../../actions/toolbox";
 
-export function showEditorContextMenu(event, editor, location) {
+export function showEditorContextMenu(event, editor, lineObject, location) {
   return async ({ dispatch, getState }) => {
     const { source } = location;
     const state = getState();
@@ -63,9 +63,9 @@ export function showEditorContextMenu(event, editor, location) {
         location,
         isPaused,
         editorWrappingEnabled,
-        selectionText: editor.codeMirror.getSelection().trim(),
-        isTextSelected: editor.codeMirror.somethingSelected(),
-        editor,
+        selectionText: editor.getSelectedText(),
+        isTextSelected: editor.isTextSelected(),
+        lineObject,
         isSourceOnIgnoreList,
         dispatch,
       })
@@ -339,7 +339,7 @@ function editorMenuItems({
   isTextSelected,
   isPaused,
   editorWrappingEnabled,
-  editor,
+  lineObject,
   isSourceOnIgnoreList,
   dispatch,
 }) {
@@ -368,14 +368,8 @@ function editorMenuItems({
     blackBoxMenuItem(source, blackboxedRanges, isSourceOnIgnoreList, dispatch)
   );
 
-  const startLine = toSourceLine(
-    source.id,
-    editor.codeMirror.getCursor("from").line
-  );
-  const endLine = toSourceLine(
-    source.id,
-    editor.codeMirror.getCursor("to").line
-  );
+  const startLine = toSourceLine(source.id, lineObject.from.line);
+  const endLine = toSourceLine(source.id, lineObject.to.line);
 
   // Find any blackbox ranges that exist for the selected lines
   const blackboxRange = findBlackBoxRange(source, blackboxedRanges, {
@@ -400,10 +394,7 @@ function editorMenuItems({
     items.push(
       blackBoxSourceLinesMenuItem(
         source,
-        {
-          from: editor.codeMirror.getCursor("from"),
-          to: editor.codeMirror.getCursor("to"),
-        },
+        lineObject,
         blackboxedRanges,
         isSourceOnIgnoreList,
         null,
diff --git a/devtools/client/debugger/src/components/Editor/Breakpoints.css b/devtools/client/debugger/src/components/Editor/Breakpoints.css
index 92121e0f46..4983688031 100644
--- a/devtools/client/debugger/src/components/Editor/Breakpoints.css
+++ b/devtools/client/debugger/src/components/Editor/Breakpoints.css
@@ -95,12 +95,16 @@
   right: -16px;
 }
 
-.new-breakpoint.has-condition .CodeMirror-gutter-wrapper svg {
+.new-breakpoint.has-condition .CodeMirror-gutter-wrapper svg,
+/* Codemirror 6*/
+.cm6-gutter-breakpoint .breakpoint-marker.has-condition svg {
   fill: var(--breakpoint-condition-fill);
   stroke: var(--breakpoint-condition-stroke);
 }
 
-.new-breakpoint.has-log .CodeMirror-gutter-wrapper svg {
+.new-breakpoint.has-log .CodeMirror-gutter-wrapper svg,
+/* Codemirror 6*/
+.cm6-gutter-breakpoint .breakpoint-marker.has-log svg {
   fill: var(--logpoint-fill);
   stroke: var(--logpoint-stroke);
 }
diff --git a/devtools/client/debugger/src/components/Editor/ConditionalPanel.css b/devtools/client/debugger/src/components/Editor/ConditionalPanel.css
index 4ce8dbcd8c..1aeac91604 100644
--- a/devtools/client/debugger/src/components/Editor/ConditionalPanel.css
+++ b/devtools/client/debugger/src/components/Editor/ConditionalPanel.css
@@ -37,3 +37,8 @@
   /* Match the color of the placeholder text to existing inputs in the Debugger */
   color: var(--theme-text-color-alt);
 }
+
+/* Removing the line padding for Codemirror 6 */
+.cm-line:has(div.conditional-breakpoint-panel) {
+  padding: 0;
+}
diff --git a/devtools/client/debugger/src/components/Editor/ConditionalPanel.js b/devtools/client/debugger/src/components/Editor/ConditionalPanel.js
index 97876f2f00..4e6f0b58ea 100644
--- a/devtools/client/debugger/src/components/Editor/ConditionalPanel.js
+++ b/devtools/client/debugger/src/components/Editor/ConditionalPanel.js
@@ -11,7 +11,8 @@ import ReactDOM from "devtools/client/shared/vendor/react-dom";
 import PropTypes from "devtools/client/shared/vendor/react-prop-types";
 import { connect } from "devtools/client/shared/vendor/react-redux";
 import { toEditorLine } from "../../utils/editor/index";
-import { prefs } from "../../utils/prefs";
+import { createEditor } from "../../utils/editor/create-editor";
+import { prefs, features } from "../../utils/prefs";
 import actions from "../../actions/index";
 
 import {
@@ -21,6 +22,7 @@ import {
 } from "../../selectors/index";
 
 const classnames = require("resource://devtools/client/shared/classnames.js");
+const CONDITIONAL_BP_MARKER = "conditional-breakpoint-panel-marker";
 
 function addNewLine(doc) {
   const cursor = doc.getCursor();
@@ -49,6 +51,7 @@ export class ConditionalPanel extends PureComponent {
       log: PropTypes.bool.isRequired,
       openConditionalPanel: PropTypes.func.isRequired,
       setBreakpointOptions: PropTypes.func.isRequired,
+      selectedSource: PropTypes.object.isRequired,
     };
   }
 
@@ -111,17 +114,53 @@ export class ConditionalPanel extends PureComponent {
     }
   };
 
+  showConditionalPanel(prevProps) {
+    const { location, editor, breakpoint, selectedSource } = this.props;
+    // When breakpoint is removed
+    if (prevProps?.breakpoint && !breakpoint) {
+      editor.removeLineContentMarker(CONDITIONAL_BP_MARKER);
+      return;
+    }
+    if (selectedSource.id !== location.source.id) {
+      editor.removeLineContentMarker(CONDITIONAL_BP_MARKER);
+      return;
+    }
+    const editorLine = toEditorLine(location.source.id, location.line || 0);
+    editor.setLineContentMarker({
+      id: CONDITIONAL_BP_MARKER,
+      condition: line => line == editorLine,
+      createLineElementNode: () => {
+        // Create a Codemirror 5 editor for the breakpoint panel
+        // TODO: Switch to use Codemirror 6 version Bug 1890205
+        const breakpointPanelEditor = createEditor();
+        breakpointPanelEditor.appendToLocalElement(
+          document.createElement("div")
+        );
+        return this.renderConditionalPanel(this.props, breakpointPanelEditor);
+      },
+    });
+  }
+
   // FIXME: https://bugzilla.mozilla.org/show_bug.cgi?id=1774507
   UNSAFE_componentWillMount() {
-    return this.renderToWidget(this.props);
+    if (features.codemirrorNext) {
+      this.showConditionalPanel();
+    } else {
+      this.renderToWidget(this.props);
+    }
   }
 
   // FIXME: https://bugzilla.mozilla.org/show_bug.cgi?id=1774507
   UNSAFE_componentWillUpdate() {
-    return this.clearConditionalPanel();
+    if (!features.codemirrorNext) {
+      this.clearConditionalPanel();
+    }
   }
 
-  componentDidUpdate() {
+  componentDidUpdate(prevProps) {
+    if (features.codemirrorNext) {
+      this.showConditionalPanel(prevProps);
+    }
     this.keepFocusOnInput();
   }
 
@@ -129,7 +168,12 @@ export class ConditionalPanel extends PureComponent {
     // This is called if CodeMirror is re-initializing itself before the
     // user closes the conditional panel. Clear the widget, and re-render it
     // as soon as this component gets remounted
-    return this.clearConditionalPanel();
+    const { editor } = this.props;
+    if (features.codemirrorNext) {
+      editor.removeLineContentMarker(CONDITIONAL_BP_MARKER);
+    } else {
+      this.clearConditionalPanel();
+    }
   }
 
   renderToWidget(props) {
@@ -141,7 +185,7 @@ export class ConditionalPanel extends PureComponent {
     const editorLine = toEditorLine(location.source.id, location.line || 0);
     this.cbPanel = editor.codeMirror.addLineWidget(
       editorLine,
-      this.renderConditionalPanel(props),
+      this.renderConditionalPanel(props, editor),
       {
         coverGutter: true,
         noHScroll: true,
@@ -168,8 +212,8 @@ export class ConditionalPanel extends PureComponent {
     }
   }
 
-  createEditor = input => {
-    const { log, editor, closeConditionalPanel } = this.props;
+  createEditor = (input, editor) => {
+    const { log, closeConditionalPanel } = this.props;
     const codeMirror = editor.CodeMirror.fromTextArea(input, {
       mode: "javascript",
       theme: "mozilla",
@@ -189,8 +233,12 @@ export class ConditionalPanel extends PureComponent {
 
     codeMirror.on("blur", (cm, e) => {
       if (
-        e?.relatedTarget &&
-        e.relatedTarget.closest(".conditional-breakpoint-panel")
+        // if there is no event
+        // or if the focus is the conditional panel
+        // do not close the conditional panel
+        !e ||
+        (e?.relatedTarget &&
+          e.relatedTarget.closest(".conditional-breakpoint-panel"))
       ) {
         return;
       }
@@ -217,7 +265,7 @@ export class ConditionalPanel extends PureComponent {
     return log ? options.logValue : options.condition;
   }
 
-  renderConditionalPanel(props) {
+  renderConditionalPanel(props, editor) {
     const { log } = props;
     const defaultValue = this.getDefaultValue();
 
@@ -239,7 +287,7 @@ export class ConditionalPanel extends PureComponent {
         ),
         textarea({
           defaultValue,
-          ref: input => this.createEditor(input),
+          ref: input => this.createEditor(input, editor),
         })
       ),
       panel
diff --git a/devtools/client/debugger/src/components/Editor/Editor.css b/devtools/client/debugger/src/components/Editor/Editor.css
index f28833747d..d2f55ed6db 100644
--- a/devtools/client/debugger/src/components/Editor/Editor.css
+++ b/devtools/client/debugger/src/components/Editor/Editor.css
@@ -146,7 +146,9 @@ html[dir="rtl"] .editor-mount {
 .new-debug-line-error .CodeMirror-activeline-background {
   display: none;
 }
-.highlight-line .CodeMirror-line {
+.highlight-line .CodeMirror-line,
+/* For CM6 */
+.cm-editor .cm-line.highlight-line {
   animation-name: fade-highlight-out;
   animation-duration: var(--highlight-line-duration);
   animation-timing-function: ease-out;
diff --git a/devtools/client/debugger/src/components/Editor/Footer.js b/devtools/client/debugger/src/components/Editor/Footer.js
index 69c7b52b68..278bc1dad7 100644
--- a/devtools/client/debugger/src/components/Editor/Footer.js
+++ b/devtools/client/debugger/src/components/Editor/Footer.js
@@ -459,8 +459,6 @@ const mapStateToProps = state => {
       : null,
     isSourceActorWithSourceMap: isSourceActorWithSourceMapProp,
 
-    sourceMapURL: selectedLocation?.sourceActor.sourceMapURL,
-
     areSourceMapsEnabled: areSourceMapsEnabledProp,
     shouldSelectOriginalLocation: getShouldSelectOriginalLocation(state),
   };
diff --git a/devtools/client/debugger/src/components/Editor/HighlightLine.js b/devtools/client/debugger/src/components/Editor/HighlightLine.js
index 8639128905..0df0fa482e 100644
--- a/devtools/client/debugger/src/components/Editor/HighlightLine.js
+++ b/devtools/client/debugger/src/components/Editor/HighlightLine.js
@@ -2,10 +2,20 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
 
+/**
+ * Uses of this panel are:-
+ * - Highlight line when source is opened using view source links from other panels
+ * - Highlight line with function or class from an Outline search result selection
+ * - Highlight line from a Quick open panel search result selection
+ * - Highlight the last selected line when a source is selected
+ * - Highlight the breakpoint line when the breakpoint is selected
+ */
+
 import { Component } from "devtools/client/shared/vendor/react";
 import PropTypes from "devtools/client/shared/vendor/react-prop-types";
 import {
   toEditorLine,
+  fromEditorLine,
   endOperation,
   startOperation,
 } from "../../utils/editor/index";
@@ -20,6 +30,7 @@ import {
   getCurrentThread,
   getShouldHighlightSelectedLocation,
 } from "../../selectors/index";
+import { features } from "../../utils/prefs";
 
 function isDebugLine(selectedFrame, selectedLocation) {
   if (!selectedFrame) {
@@ -32,14 +43,6 @@ function isDebugLine(selectedFrame, selectedLocation) {
   );
 }
 
-function isDocumentReady(selectedLocation, selectedSourceTextContent) {
-  return (
-    selectedLocation &&
-    selectedSourceTextContent &&
-    hasDocument(selectedLocation.source.id)
-  );
-}
-
 export class HighlightLine extends Component {
   isStepping = false;
   previousEditorLine = null;
@@ -56,30 +59,34 @@ export class HighlightLine extends Component {
       selectedFrame: PropTypes.object,
       selectedLocation: PropTypes.object.isRequired,
       selectedSourceTextContent: PropTypes.object.isRequired,
+      shouldHighlightSelectedLocation: PropTypes.func.isRequired,
+      editor: PropTypes.object,
     };
   }
 
   shouldComponentUpdate(nextProps) {
-    const { selectedLocation, selectedSourceTextContent } = nextProps;
-    return this.shouldSetHighlightLine(
-      selectedLocation,
-      selectedSourceTextContent
-    );
+    return this.shouldSetHighlightLine(nextProps);
   }
 
   componentDidUpdate(prevProps) {
-    this.completeHighlightLine(prevProps);
+    this.highlightLine(prevProps);
   }
 
   componentDidMount() {
-    this.completeHighlightLine(null);
+    this.highlightLine(null);
   }
 
-  shouldSetHighlightLine(selectedLocation, selectedSourceTextContent) {
-    const { line } = selectedLocation;
-    const editorLine = toEditorLine(selectedLocation.source.id, line);
+  shouldSetHighlightLine({ selectedLocation, selectedSourceTextContent }) {
+    const editorLine = toEditorLine(
+      selectedLocation.source.id,
+      selectedLocation.line
+    );
 
-    if (!isDocumentReady(selectedLocation, selectedSourceTextContent)) {
+    if (
+      !selectedLocation ||
+      !selectedSourceTextContent ||
+      (!features.codemirrorNext && !hasDocument(selectedLocation.source.id))
+    ) {
       return false;
     }
 
@@ -90,58 +97,61 @@ export class HighlightLine extends Component {
     return true;
   }
 
-  completeHighlightLine(prevProps) {
-    const {
-      pauseCommand,
-      selectedLocation,
-      selectedFrame,
-      selectedSourceTextContent,
-      shouldHighlightSelectedLocation,
-    } = this.props;
+  highlightLine(prevProps) {
+    const { pauseCommand, shouldHighlightSelectedLocation } = this.props;
     if (pauseCommand) {
       this.isStepping = true;
     }
 
-    startOperation();
+    if (!features.codemirrorNext) {
+      startOperation();
+    }
     if (prevProps) {
-      this.clearHighlightLine(
-        prevProps.selectedLocation,
-        prevProps.selectedSourceTextContent
-      );
+      this.clearHighlightLine(prevProps);
     }
     if (shouldHighlightSelectedLocation) {
-      this.setHighlightLine(
-        selectedLocation,
-        selectedFrame,
-        selectedSourceTextContent
-      );
+      this.setHighlightLine();
+    }
+    if (!features.codemirrorNext) {
+      endOperation();
     }
-    endOperation();
   }
 
-  setHighlightLine(selectedLocation, selectedFrame, selectedSourceTextContent) {
-    const { line } = selectedLocation;
-    if (
-      !this.shouldSetHighlightLine(selectedLocation, selectedSourceTextContent)
-    ) {
+  setHighlightLine() {
+    const { selectedLocation, selectedFrame, editor } = this.props;
+    if (!this.shouldSetHighlightLine(this.props)) {
       return;
     }
 
     this.isStepping = false;
     const sourceId = selectedLocation.source.id;
-    const editorLine = toEditorLine(sourceId, line);
+    const editorLine = toEditorLine(sourceId, selectedLocation.line);
     this.previousEditorLine = editorLine;
 
-    if (!line || isDebugLine(selectedFrame, selectedLocation)) {
+    if (
+      !selectedLocation.line ||
+      isDebugLine(selectedFrame, selectedLocation)
+    ) {
       return;
     }
 
-    const doc = getDocument(sourceId);
-    doc.addLineClass(editorLine, "wrap", "highlight-line");
-    this.resetHighlightLine(doc, editorLine);
+    if (features.codemirrorNext) {
+      editor.setLineContentMarker({
+        id: "highlight-line-marker",
+        lineClassName: "highlight-line",
+        condition(line) {
+          const lineNumber = fromEditorLine(sourceId, line);
+          return selectedLocation.line == lineNumber;
+        },
+      });
+    } else {
+      const doc = getDocument(sourceId);
+      doc.addLineClass(editorLine, "wrap", "highlight-line");
+    }
+    this.clearHighlightLineAfterDuration();
   }
 
-  resetHighlightLine(doc, editorLine) {
+  clearHighlightLineAfterDuration() {
     const editorWrapper = document.querySelector(".editor-wrapper");
 
     if (editorWrapper === null) {
@@ -155,20 +165,28 @@ export class HighlightLine extends Component {
       10
     );
 
-    setTimeout(
-      () => doc && doc.removeLineClass(editorLine, "wrap", "highlight-line"),
-      duration
-    );
+    setTimeout(() => this.clearHighlightLine(this.props), duration);
   }
 
-  clearHighlightLine(selectedLocation, selectedSourceTextContent) {
-    if (!isDocumentReady(selectedLocation, selectedSourceTextContent)) {
+  clearHighlightLine({ selectedLocation, selectedSourceTextContent }) {
+    if (!selectedLocation || !selectedSourceTextContent) {
+      return;
+    }
+
+    if (features.codemirrorNext) {
+      const { editor } = this.props;
+      if (editor) {
+        editor.removeLineContentMarker("highlight-line-marker");
+      }
+      return;
+    }
+
+    if (!hasDocument(selectedLocation.source.id)) {
       return;
     }
 
-    const { line } = selectedLocation;
     const sourceId = selectedLocation.source.id;
-    const editorLine = toEditorLine(sourceId, line);
+    const editorLine = toEditorLine(sourceId, selectedLocation.line);
     const doc = getDocument(sourceId);
     doc.removeLineClass(editorLine, "wrap", "highlight-line");
   }
diff --git a/devtools/client/debugger/src/components/Editor/HighlightLines.js b/devtools/client/debugger/src/components/Editor/HighlightLines.js
index e34a86aba9..e62125e5f8 100644
--- a/devtools/client/debugger/src/components/Editor/HighlightLines.js
+++ b/devtools/client/debugger/src/components/Editor/HighlightLines.js
@@ -2,8 +2,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
 
+/**
+ * Uses of this panel are:-
+ * - Highlighting lines of a function selected to be copied using the "Copy function" context menu in the Outline panel
+ */
+
 import { Component } from "devtools/client/shared/vendor/react";
 import PropTypes from "devtools/client/shared/vendor/react-prop-types";
+import { fromEditorLine } from "../../utils/editor/index";
+import { features } from "../../utils/prefs";
 
 class HighlightLines extends Component {
   static get propTypes() {
@@ -33,9 +40,19 @@ class HighlightLines extends Component {
   clearHighlightRange() {
     const { range, editor } = this.props;
 
-    const { codeMirror } = editor;
+    if (!range) {
+      return;
+    }
 
-    if (!range || !codeMirror) {
+    if (features.codemirrorNext) {
+      if (editor) {
+        editor.removeLineContentMarker("multi-highlight-line-marker");
+      }
+      return;
+    }
+
+    const { codeMirror } = editor;
+    if (!codeMirror) {
       return;
     }
 
@@ -50,14 +67,31 @@ class HighlightLines extends Component {
   highlightLineRange = () => {
     const { range, editor } = this.props;
 
-    const { codeMirror } = editor;
+    if (!range) {
+      return;
+    }
 
-    if (!range || !codeMirror) {
+    if (features.codemirrorNext) {
+      // TODO: Fix scrolling into view if its out Bug 1894725
+      if (editor) {
+        editor.setLineContentMarker({
+          id: "multi-highlight-line-marker",
+          lineClassName: "highlight-lines",
+          condition(line) {
+            const lineNumber = fromEditorLine(null, line);
+            return lineNumber >= range.start && lineNumber <= range.end;
+          },
+        });
+      }
       return;
     }
 
-    const { start, end } = range;
+    const { codeMirror } = editor;
+    if (!codeMirror) {
+      return;
+    }
 
+    const { start, end } = range;
     codeMirror.operation(() => {
       editor.alignLine(start);
       for (let line = start - 1; line < end; line++) {
diff --git a/devtools/client/debugger/src/components/Editor/InlinePreviews.js b/devtools/client/debugger/src/components/Editor/InlinePreviews.js
index ba8b08669a..56c5f5021f 100644
--- a/devtools/client/debugger/src/components/Editor/InlinePreviews.js
+++ b/devtools/client/debugger/src/components/Editor/InlinePreviews.js
@@ -3,9 +3,13 @@
  * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
 
 import React, { Component } from "devtools/client/shared/vendor/react";
+import ReactDOM from "devtools/client/shared/vendor/react-dom";
+
+import actions from "../../actions/index";
 import { div } from "devtools/client/shared/vendor/react-dom-factories";
 import PropTypes from "devtools/client/shared/vendor/react-prop-types";
 import InlinePreviewRow from "./InlinePreviewRow";
+import InlinePreview from "./InlinePreview";
 import { connect } from "devtools/client/shared/vendor/react-redux";
 import {
   getSelectedFrame,
@@ -13,6 +17,8 @@ import {
   getInlinePreviews,
 } from "../../selectors/index";
 
+import { features } from "../../utils/prefs";
+
 function hasPreviews(previews) {
   return !!previews && !!Object.keys(previews).length;
 }
@@ -31,9 +37,85 @@ class InlinePreviews extends Component {
     return hasPreviews(previews);
   }
 
+  componentDidMount() {
+    this.renderInlinePreviewMarker();
+  }
+
+  componentDidUpdate() {
+    this.renderInlinePreviewMarker();
+  }
+
+  renderInlinePreviewMarker() {
+    const {
+      editor,
+      selectedFrame,
+      selectedSource,
+      previews,
+      openElementInInspector,
+      highlightDomElement,
+      unHighlightDomElement,
+    } = this.props;
+
+    if (!features.codemirrorNext) {
+      return;
+    }
+
+    if (
+      !editor ||
+      !selectedFrame ||
+      selectedFrame.location.source.id !== selectedSource.id ||
+      !hasPreviews(previews)
+    ) {
+      editor.removeLineContentMarker("inline-preview-marker");
+      return;
+    }
+    editor.setLineContentMarker({
+      id: "inline-preview-marker",
+      condition: line => {
+        // CM6 line is 1-based unlike CM5 which is 0-based.
+        return !!previews[line - 1];
+      },
+      createLineElementNode: line => {
+        const widgetNode = document.createElement("div");
+        widgetNode.className = "inline-preview";
+
+        ReactDOM.render(
+          React.createElement(
+            React.Fragment,
+            null,
+            previews[line - 1].map(preview =>
+              React.createElement(InlinePreview, {
+                line,
+                key: `${line}-${preview.name}`,
+                variable: preview.name,
+                value: preview.value,
+                openElementInInspector,
+                highlightDomElement,
+                unHighlightDomElement,
+              })
+            )
+          ),
+          widgetNode
+        );
+        return widgetNode;
+      },
+    });
+  }
+
+  componentWillUnmount() {
+    if (!features.codemirrorNext) {
+      return;
+    }
+    this.props.editor.removeLineContentMarker("inline-preview-marker");
+  }
+
   render() {
     const { editor, selectedFrame, selectedSource, previews } = this.props;
 
+    if (features.codemirrorNext) {
+      return null;
+    }
+
     // Render only if currently open file is the one where debugger is paused
     if (
       !selectedFrame ||
@@ -77,4 +159,8 @@ const mapStateToProps = state => {
   };
 };
 
-export default connect(mapStateToProps)(InlinePreviews);
+export default connect(mapStateToProps, {
+  openElementInInspector: actions.openElementInInspectorCommand,
+  highlightDomElement: actions.highlightDomElement,
+  unHighlightDomElement: actions.unHighlightDomElement,
+})(InlinePreviews);
diff --git a/devtools/client/debugger/src/components/Editor/index.js b/devtools/client/debugger/src/components/Editor/index.js
index e21e05c11a..38040e3314 100644
--- a/devtools/client/debugger/src/components/Editor/index.js
+++ b/devtools/client/debugger/src/components/Editor/index.js
@@ -61,7 +61,6 @@ import {
   lineAtHeight,
   toSourceLine,
   getDocument,
-  scrollToPosition,
   toEditorPosition,
   getSourceLocationFromMouseEvent,
   hasDocument,
@@ -149,15 +148,15 @@ class Editor extends PureComponent {
         this.props.selectedSourceTextContent?.value ||
       nextProps.symbols !== this.props.symbols;
 
+    const shouldScroll =
+      nextProps.selectedLocation &&
+      this.shouldScrollToLocation(nextProps, editor);
+
     if (!features.codemirrorNext) {
       const shouldUpdateSize =
         nextProps.startPanelSize !== this.props.startPanelSize ||
         nextProps.endPanelSize !== this.props.endPanelSize;
 
-      const shouldScroll =
-        nextProps.selectedLocation &&
-        this.shouldScrollToLocation(nextProps, editor);
-
       if (shouldUpdateText || shouldUpdateSize || shouldScroll) {
         startOperation();
         if (shouldUpdateText) {
@@ -183,6 +182,10 @@ class Editor extends PureComponent {
       if (shouldUpdateText) {
         this.setText(nextProps, editor);
       }
+
+      if (shouldScroll) {
+        this.scrollToLocation(nextProps, editor);
+      }
     }
   }
 
@@ -238,7 +241,12 @@ class Editor extends PureComponent {
       editor.setUpdateListener(this.onEditorUpdated);
       editor.setGutterEventListeners({
         click: (event, cm, line) => this.onGutterClick(cm, line, null, event),
-        contextmenu: (event, cm, line) => this.openMenu(event, line, true),
+        contextmenu: (event, cm, line) => this.openMenu(event, line),
+      });
+      editor.setContentEventListeners({
+        click: (event, cm, line, column) => this.onClick(event, line, column),
+        contextmenu: (event, cm, line, column) =>
+          this.openMenu(event, line, column),
       });
     }
     this.setState({ editor });
@@ -278,7 +286,7 @@ class Editor extends PureComponent {
     }
   };
 
-  componentDidUpdate(prevProps) {
+  componentDidUpdate(prevProps, prevState) {
     const {
       selectedSource,
       blackboxedRanges,
@@ -295,7 +303,9 @@ class Editor extends PureComponent {
     if (features.codemirrorNext) {
       const shouldUpdateBreakableLines =
         prevProps.breakableLines.size !== this.props.breakableLines.size ||
-        prevProps.selectedSource?.id !== selectedSource.id;
+        prevProps.selectedSource?.id !== selectedSource.id ||
+        // Make sure we update after the editor has loaded
+        (!prevState.editor && !!editor);
 
       const isSourceWasm = isWasm(selectedSource.id);
 
@@ -459,7 +469,7 @@ class Editor extends PureComponent {
   };
   // Note: The line is optional, if not passed (as is likely for codemirror 6)
   // it fallsback to lineAtHeight.
-  openMenu(event, line) {
+  openMenu(event, line, ch) {
     event.stopPropagation();
     event.preventDefault();
 
@@ -508,7 +518,7 @@ class Editor extends PureComponent {
         line
       ).trim();
 
-      const lineObject = { from: { line }, to: { line } };
+      const lineObject = { from: { line, ch }, to: { line, ch } };
 
       this.props.showEditorGutterContextMenu(
         event,
@@ -523,13 +533,23 @@ class Editor extends PureComponent {
       return;
     }
 
-    const location = getSourceLocationFromMouseEvent(
-      editor,
-      selectedSource,
-      event
-    );
+    let location;
+    if (features.codemirrorNext) {
+      location = createLocation({
+        source: selectedSource,
+        line: fromEditorLine(
+          selectedSource.id,
+          line,
+          isWasm(selectedSource.id)
+        ),
+        column: isWasm(selectedSource.id) ? 0 : ch + 1,
+      });
+    } else {
+      location = getSourceLocationFromMouseEvent(editor, selectedSource, event);
+    }
 
-    this.props.showEditorContextMenu(event, editor, location);
+    const lineObject = editor.getSelectionCursor();
+    this.props.showEditorContextMenu(event, editor, lineObject, location);
   }
 
   /**
@@ -617,16 +637,29 @@ class Editor extends PureComponent {
     );
   };
 
-  onClick(e) {
+  onClick(e, line, ch) {
     const { selectedSource, updateCursorPosition, jumpToMappedLocation } =
       this.props;
 
     if (selectedSource) {
-      const sourceLocation = getSourceLocationFromMouseEvent(
-        this.state.editor,
-        selectedSource,
-        e
-      );
+      let sourceLocation;
+      if (features.codemirrorNext) {
+        sourceLocation = createLocation({
+          source: selectedSource,
+          line: fromEditorLine(
+            selectedSource.id,
+            line,
+            isWasm(selectedSource.id)
+          ),
+          column: isWasm(selectedSource.id) ? 0 : ch + 1,
+        });
+      } else {
+        sourceLocation = getSourceLocationFromMouseEvent(
+          this.state.editor,
+          selectedSource,
+          e
+        );
+      }
 
       if (e.metaKey && e.altKey) {
         jumpToMappedLocation(sourceLocation);
@@ -664,8 +697,7 @@ class Editor extends PureComponent {
       const lineText = doc.getLine(line);
       column = Math.max(column, getIndentation(lineText));
     }
-
-    scrollToPosition(editor.codeMirror, line, column);
+    editor.scrollTo(line, column);
   }
 
   setText(props, editor) {
@@ -774,6 +806,7 @@ class Editor extends PureComponent {
     };
   }
 
+  // eslint-disable-next-line complexity
   renderItems() {
     const {
       selectedSource,
@@ -788,19 +821,44 @@ class Editor extends PureComponent {
     } = this.props;
     const { editor } = this.state;
 
+    if (!selectedSource || !editor) {
+      return null;
+    }
+
     if (features.codemirrorNext) {
       return React.createElement(
         React.Fragment,
         null,
-        React.createElement(Breakpoints, {
-          editor,
-        }),
+        React.createElement(Breakpoints, { editor }),
         React.createElement(DebugLine, { editor, selectedSource }),
-        React.createElement(Exceptions, { editor })
+        React.createElement(HighlightLine, { editor }),
+        React.createElement(Exceptions, { editor }),
+        conditionalPanelLocation
+          ? React.createElement(ConditionalPanel, {
+              editor,
+              selectedSource,
+            })
+          : null,
+        isPaused &&
+          inlinePreviewEnabled &&
+          (!selectedSource.isOriginal ||
+            selectedSource.isPrettyPrinted ||
+            mapScopesEnabled)
+          ? React.createElement(InlinePreviews, {
+              editor,
+              selectedSource,
+            })
+          : null,
+        highlightedLineRange
+          ? React.createElement(HighlightLines, {
+              editor,
+              range: highlightedLineRange,
+            })
+          : null
       );
     }
 
-    if (!selectedSource || !editor || !getDocument(selectedSource.id)) {
+    if (!getDocument(selectedSource.id)) {
       return null;
     }
     return div(
diff --git a/devtools/client/debugger/src/utils/editor/index.js b/devtools/client/debugger/src/utils/editor/index.js
index e729388acf..3146581fdd 100644
--- a/devtools/client/debugger/src/utils/editor/index.js
+++ b/devtools/client/debugger/src/utils/editor/index.js
@@ -106,50 +106,6 @@ export function toSourceLine(sourceId, line) {
   return line + 1;
 }
 
-export function scrollToPosition(codeMirror, line, column) {
-  // For all cases where these are on the first line and column,
-  // avoid the possibly slow computation of cursor location on large bundles.
-  if (!line && !column) {
-    codeMirror.scrollTo(0, 0);
-    return;
-  }
-
-  const { top, left } = codeMirror.charCoords({ line, ch: column }, "local");
-
-  if (!isVisible(codeMirror, top, left)) {
-    const scroller = codeMirror.getScrollerElement();
-    const centeredX = Math.max(left - scroller.offsetWidth / 2, 0);
-    const centeredY = Math.max(top - scroller.offsetHeight / 2, 0);
-
-    codeMirror.scrollTo(centeredX, centeredY);
-  }
-}
-
-function isVisible(codeMirror, top, left) {
-  function withinBounds(x, min, max) {
-    return x >= min && x <= max;
-  }
-
-  const scrollArea = codeMirror.getScrollInfo();
-  const charWidth = codeMirror.defaultCharWidth();
-  const fontHeight = codeMirror.defaultTextHeight();
-  const { scrollTop, scrollLeft } = codeMirror.doc;
-
-  const inXView = withinBounds(
-    left,
-    scrollLeft,
-    scrollLeft + (scrollArea.clientWidth - 30) - charWidth
-  );
-
-  const inYView = withinBounds(
-    top,
-    scrollTop,
-    scrollTop + scrollArea.clientHeight - fontHeight
-  );
-
-  return inXView && inYView;
-}
-
 export function getLocationsInViewport(
   { codeMirror },
   // Offset represents an allowance of characters or lines offscreen to improve
diff --git a/devtools/client/debugger/src/utils/editor/tests/editor.spec.js b/devtools/client/debugger/src/utils/editor/tests/editor.spec.js
index b3fcad17ff..3917adaba1 100644
--- a/devtools/client/debugger/src/utils/editor/tests/editor.spec.js
+++ b/devtools/client/debugger/src/utils/editor/tests/editor.spec.js
@@ -6,7 +6,6 @@ import {
   toEditorLine,
   toEditorPosition,
   toSourceLine,
-  scrollToPosition,
   markText,
   lineAtHeight,
   getSourceLocationFromMouseEvent,
@@ -82,17 +81,6 @@ const codeMirror = {
 
 const editor = { codeMirror };
 
-describe("scrollToPosition", () => {
-  it("calls codemirror APIs charCoords, getScrollerElement, scrollTo", () => {
-    scrollToPosition(codeMirror, 60, 123);
-    expect(codeMirror.charCoords).toHaveBeenCalledWith(
-      { line: 60, ch: 123 },
-      "local"
-    );
-    expect(codeMirror.scrollTo).toHaveBeenCalledWith(0, 50);
-  });
-});
-
 describe("markText", () => {
   it("calls codemirror API markText & returns marker", () => {
     const loc = {
diff --git a/devtools/client/debugger/src/utils/source.js b/devtools/client/debugger/src/utils/source.js
index 91a02778e2..1a2b453ec2 100644
--- a/devtools/client/debugger/src/utils/source.js
+++ b/devtools/client/debugger/src/utils/source.js
@@ -209,6 +209,15 @@ function resolveFileURL(
 }
 
 export function getFormattedSourceId(id) {
+  if (typeof id != "string") {
+    console.error(
+      "Expected source id to be a string, got",
+      typeof id,
+      " | id:",
+      id
+    );
+    return "";
+  }
   return id.substring(id.lastIndexOf("/") + 1);
 }
 
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js b/devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js
index 1065674186..49b3d3ffce 100644
--- a/devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-event-breakpoints.js
@@ -7,6 +7,7 @@
 add_task(async function () {
   await pushPref("dom.element.invokers.enabled", true);
   await pushPref("dom.element.popover.enabled", true);
+  await pushPref("dom.events.textevent.enabled", true);
 
   const dbg = await initDebugger(
     "doc-event-breakpoints.html",
@@ -151,6 +152,15 @@ add_task(async function () {
   assertPausedAtSourceAndLine(dbg, eventBreakpointsSource.id, 63);
   await resume(dbg);
 
+  info("Test textInput");
+  await toggleEventBreakpoint(dbg, "Keyboard", "event.keyboard.textInput");
+  invokeOnElement("#focus-text", "focus");
+  EventUtils.sendChar("N");
+  await waitForPaused(dbg);
+  assertPausedAtSourceAndLine(dbg, eventBreakpointsSource.id, 98);
+  await resume(dbg);
+  await toggleEventBreakpoint(dbg, "Keyboard", "event.keyboard.textInput");
+
   info(`Check that breakpoint can be set on "scrollend"`);
   await toggleEventBreakpoint(dbg, "Control", "event.control.scrollend");
 
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-javascript-tracer.js b/devtools/client/debugger/test/mochitest/browser_dbg-javascript-tracer.js
index bfa2447474..29335af768 100644
--- a/devtools/client/debugger/test/mochitest/browser_dbg-javascript-tracer.js
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-javascript-tracer.js
@@ -12,6 +12,19 @@ add_task(async function () {
 
   const dbg = await initDebugger("doc-scripts.html");
 
+  // Add an iframe before starting the tracer to later check for key event on it
+  const preExistingIframeBrowsingContext = await SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [],
+    async function () {
+      const iframe = content.document.createElement("iframe");
+      iframe.src = `data:text/html,<input type="text" value="pre existing iframe" onkeydown="console.log('keydown')" />`;
+      content.document.body.appendChild(iframe);
+      await new Promise(resolve => (iframe.onload = resolve));
+      return iframe.contentWindow.browsingContext;
+    }
+  );
+
   info("Enable the tracing");
   await clickElement(dbg, "trace");
 
@@ -55,6 +68,38 @@ add_task(async function () {
   await hasConsoleMessage(dbg, "DOM | click");
   await hasConsoleMessage(dbg, "λ simple");
 
+  const iframeBrowsingContext = await SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [],
+    async function () {
+      const iframe = content.document.createElement("iframe");
+      iframe.src = `data:text/html,<input type="text" value="new iframe" onkeypress="console.log('keypress')" />`;
+      content.document.body.appendChild(iframe);
+      await new Promise(resolve => (iframe.onload = resolve));
+      iframe.contentWindow.document.querySelector("input").focus();
+      return iframe.contentWindow.browsingContext;
+    }
+  );
+
+  await BrowserTestUtils.synthesizeKey("x", {}, iframeBrowsingContext);
+  await hasConsoleMessage(dbg, "DOM | keypress");
+  await hasConsoleMessage(dbg, "λ onkeypress");
+
+  await SpecialPowers.spawn(
+    preExistingIframeBrowsingContext,
+    [],
+    async function () {
+      content.document.querySelector("input").focus();
+    }
+  );
+  await BrowserTestUtils.synthesizeKey(
+    "x",
+    {},
+    preExistingIframeBrowsingContext
+  );
+  await hasConsoleMessage(dbg, "DOM | keydown");
+  await hasConsoleMessage(dbg, "λ onkeydown");
+
   // Test Blackboxing
   info("Clear the console from previous traces");
   const { hud } = await dbg.toolbox.getPanel("webconsole");
diff --git a/devtools/client/debugger/test/mochitest/examples/event-breakpoints.js b/devtools/client/debugger/test/mochitest/examples/event-breakpoints.js
index f9aa16b858..3d8163a8c4 100644
--- a/devtools/client/debugger/test/mochitest/examples/event-breakpoints.js
+++ b/devtools/client/debugger/test/mochitest/examples/event-breakpoints.js
@@ -91,4 +91,9 @@ function onBeforeToggle(event) {
 popover.addEventListener("toggle", onToggle);
 function onToggle(event) {
   console.log("toggle", event);
-}
\ No newline at end of file
+}
+
+document.getElementById("focus-text").addEventListener("textInput", onTextInput);
+function onTextInput() {
+  console.log("textInput");
+}
diff --git a/devtools/client/framework/test/browser.toml b/devtools/client/framework/test/browser.toml
index e7d979ebb3..c0faa66301 100644
--- a/devtools/client/framework/test/browser.toml
+++ b/devtools/client/framework/test/browser.toml
@@ -183,6 +183,9 @@ skip-if = [
   "http2",
 ]
 
+["browser_toolbox_many_toggles.js"]
+skip-if = ["os == 'win'"] # Content process killing throws on Window
+
 ["browser_toolbox_meatball.js"]
 
 ["browser_toolbox_options.js"]
diff --git a/devtools/client/framework/test/browser_toolbox_many_toggles.js b/devtools/client/framework/test/browser_toolbox_many_toggles.js
new file mode 100644
index 0000000000..1841ce1874
--- /dev/null
+++ b/devtools/client/framework/test/browser_toolbox_many_toggles.js
@@ -0,0 +1,50 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Bug 1898490: DevTools may prevents opening when some random content process is being destroyed
+// in middle of DevTools initialization.
+// So try opening DevTools a couple of times while destroying content processes in the background.
+
+const URL =
+  "data:text/html;charset=utf8,test many toggles with other content process destructions";
+
+add_task(async function () {
+  const tab = await addTab(URL);
+
+  const ProcessTools = Cc["@mozilla.org/processtools-service;1"].getService(
+    Ci.nsIProcessToolsService
+  );
+
+  const openedTabs = [];
+  const interval = setInterval(() => {
+    // Close the process specific to about:home, which is using a privilegedabout process type
+    const pid = ChromeUtils.getAllDOMProcesses().filter(
+      r => r.remoteType == "privilegedabout"
+    )[0]?.osPid;
+    if (!pid) {
+      return;
+    }
+    ProcessTools.kill(pid);
+    // The privilegedabout process wouldn't be automatically re-created, so open a new tab to force creating a new process.
+    openedTabs.push(BrowserTestUtils.addTab(gBrowser, "about:home"));
+  });
+
+  info(
+    "Open/close DevTools many times in a row while some processes get destroyed"
+  );
+  for (let i = 0; i < 5; i++) {
+    const toolbox = await gDevTools.showToolboxForTab(tab, {
+      toolId: "webconsole",
+    });
+    await toolbox.destroy();
+  }
+
+  clearInterval(interval);
+
+  info("Close all tabs that were used to spawn a new content process");
+  for (const tab of openedTabs) {
+    await removeTab(tab);
+  }
+});
diff --git a/devtools/client/framework/test/node/README.md b/devtools/client/framework/test/node/README.md
index 9fb86edfc5..6530aaf873 100644
--- a/devtools/client/framework/test/node/README.md
+++ b/devtools/client/framework/test/node/README.md
@@ -19,4 +19,4 @@ The tests run on try on linux64 platforms. The complete name of the try job is `
 Adding the tests to a try push depends on the try selector you are using.
 - try fuzzy: look for the job named `source-test-node-devtools-tests`
 
-The configuration file for try can be found at `taskcluster/ci/source-test/node.yml`
+The configuration file for try can be found at `taskcluster/kinds/source-test/node.yml`
diff --git a/devtools/client/fronts/inspector/rule-rewriter.js b/devtools/client/fronts/inspector/rule-rewriter.js
index 30d1cf88d2..9fd84ccd8c 100644
--- a/devtools/client/fronts/inspector/rule-rewriter.js
+++ b/devtools/client/fronts/inspector/rule-rewriter.js
@@ -12,7 +12,9 @@
 
 "use strict";
 
-const { getCSSLexer } = require("resource://devtools/shared/css/lexer.js");
+const {
+  InspectorCSSParserWrapper,
+} = require("resource://devtools/shared/css/lexer.js");
 const {
   COMMENT_PARSING_HEURISTIC_BYPASS_CHAR,
   escapeCSSComment,
@@ -194,7 +196,7 @@ RuleRewriter.prototype = {
     // into "url(;)" by this code -- due to the way "url(...)" is
     // parsed as a single token.
     text = text.replace(/;$/, "");
-    const lexer = getCSSLexer(text);
+    const lexer = new InspectorCSSParserWrapper(text, { trackEOFChars: true });
 
     let result = "";
     let previousOffset = 0;
@@ -210,7 +212,7 @@ RuleRewriter.prototype = {
       // We set the location of the paren in a funny way, to handle
       // the case where we've seen a function token, where the paren
       // appears at the end.
-      parenStack.push({ closer, offset: result.length - 1 });
+      parenStack.push({ closer, offset: result.length - 1, token });
       previousOffset = token.endOffset;
     };
 
@@ -223,6 +225,18 @@ RuleRewriter.prototype = {
           return true;
         }
 
+        // We need to handle non-closed url function differently, as performEOFFixup will
+        // only automatically close missing parenthesis `url`.
+        // In such case, don't do anything here.
+        if (
+          paren.closer === ")" &&
+          closer == null &&
+          paren.token.tokenType === "Function" &&
+          paren.token.value === "url"
+        ) {
+          return true;
+        }
+
         // Found a non-matching closing paren, so quote it.  Note that
         // these are processed in reverse order.
         result =
@@ -234,50 +248,43 @@ RuleRewriter.prototype = {
       return false;
     };
 
-    while (true) {
-      const token = lexer.nextToken();
-      if (!token) {
-        break;
-      }
-
-      if (token.tokenType === "symbol") {
-        switch (token.text) {
-          case ";":
-            // We simply drop the ";" here.  This lets us cope with
-            // declarations that don't have a ";" and also other
-            // termination.  The caller handles adding the ";" again.
+    let token;
+    while ((token = lexer.nextToken())) {
+      switch (token.tokenType) {
+        case "Semicolon":
+          // We simply drop the ";" here.  This lets us cope with
+          // declarations that don't have a ";" and also other
+          // termination.  The caller handles adding the ";" again.
+          result += text.substring(previousOffset, token.startOffset);
+          previousOffset = token.endOffset;
+          break;
+
+        case "CurlyBracketBlock":
+          pushParen(token, "}");
+          break;
+
+        case "ParenthesisBlock":
+        case "Function":
+          pushParen(token, ")");
+          break;
+
+        case "SquareBracketBlock":
+          pushParen(token, "]");
+          break;
+
+        case "CloseCurlyBracket":
+        case "CloseParenthesis":
+        case "CloseSquareBracket":
+          // Did we find an unmatched close bracket?
+          if (!popSomeParens(token.text)) {
+            // Copy out text from |previousOffset|.
             result += text.substring(previousOffset, token.startOffset);
+            // Quote the offending symbol.
+            result += "\\" + token.text;
             previousOffset = token.endOffset;
-            break;
-
-          case "{":
-            pushParen(token, "}");
-            break;
-
-          case "(":
-            pushParen(token, ")");
-            break;
-
-          case "[":
-            pushParen(token, "]");
-            break;
-
-          case "}":
-          case ")":
-          case "]":
-            // Did we find an unmatched close bracket?
-            if (!popSomeParens(token.text)) {
-              // Copy out text from |previousOffset|.
-              result += text.substring(previousOffset, token.startOffset);
-              // Quote the offending symbol.
-              result += "\\" + token.text;
-              previousOffset = token.endOffset;
-              anySanitized = true;
-            }
-            break;
-        }
-      } else if (token.tokenType === "function") {
-        pushParen(token, ")");
+            anySanitized = true;
+          }
+          break;
       }
     }
 
@@ -286,7 +293,8 @@ RuleRewriter.prototype = {
 
     // Copy out any remaining text, then any needed terminators.
     result += text.substring(previousOffset, text.length);
-    const eofFixup = lexer.performEOFFixup("", true);
+
+    const eofFixup = lexer.performEOFFixup("");
     if (eofFixup) {
       anySanitized = true;
       result += eofFixup;
diff --git a/devtools/client/fronts/walker.js b/devtools/client/fronts/walker.js
index 5cffef612d..6d364f07a1 100644
--- a/devtools/client/fronts/walker.js
+++ b/devtools/client/fronts/walker.js
@@ -149,13 +149,6 @@ class WalkerFront extends FrontClassWithSpec(walkerSpec) {
   }
 
   async getIdrefNode(queryNode, id) {
-    // @backward-compat { version 125 } getIdrefNode was added in 125, so the whole if
-    // block below can be removed once 125 hits release.
-    if (!this.traits.hasGetIdrefNode) {
-      const doc = await this.document(queryNode);
-      return this.querySelector(doc, "#" + id);
-    }
-
     const response = await super.getIdrefNode(queryNode, id);
     return response.node;
   }
diff --git a/devtools/client/inspector/rules/test/browser_part2.toml b/devtools/client/inspector/rules/test/browser_part2.toml
index 1cffe88e6e..19d7e2997b 100644
--- a/devtools/client/inspector/rules/test/browser_part2.toml
+++ b/devtools/client/inspector/rules/test/browser_part2.toml
@@ -181,6 +181,8 @@ skip-if = [
 
 ["browser_rules_keyframeLineNumbers.js"]
 
+["browser_rules_keyframes-rule-nested.js"]
+
 ["browser_rules_keyframes-rule-shadowdom.js"]
 
 ["browser_rules_keyframes-rule_01.js"]
diff --git a/devtools/client/inspector/rules/test/browser_rules_keyframes-rule-nested.js b/devtools/client/inspector/rules/test/browser_rules_keyframes-rule-nested.js
new file mode 100644
index 0000000000..97b4b21a65
--- /dev/null
+++ b/devtools/client/inspector/rules/test/browser_rules_keyframes-rule-nested.js
@@ -0,0 +1,89 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test that nested @keyframes rules are displayed correctly in the rule view
+
+const TEST_URI = `data:text/html,${encodeURIComponent(`
+  <style>
+    body {
+      animation-name: in-layer,
+                      in-starting-style,
+                      in-media,
+                      in-container;
+      animation-duration: 1s, 2s, 3s, 4s;
+      border: 4px solid;
+      outline: 4px solid;
+    }
+
+    @layer {
+      @keyframes in-layer {
+        from { color: red; }
+        to   { color: blue; }
+      }
+    }
+
+    @starting-style {
+      /* keyframes is considered as being outside of @starting-style */
+      @keyframes in-starting-style {
+        from { border-color: tomato; }
+        to   { border-color: gold; }
+      }
+    }
+
+    @media screen {
+      @keyframes in-media {
+        from { outline-color: purple; }
+        to   { outline-color: pink; }
+      }
+    }
+
+    @container (width > 0px) {
+      /* keyframes is considered as being outside of @container */
+      @keyframes in-container {
+        from { background-color: green; }
+        to   { background-color: lime; }
+      }
+    }
+  </style>
+  <h1>Nested <code>@keyframes</code></h1>
+`)}`;
+
+add_task(async function () {
+  await pushPref("layout.css.starting-style-at-rules.enabled", true);
+  await addTab(TEST_URI);
+  const { inspector, view } = await openRuleView();
+
+  await selectNode("body", inspector);
+  const headers = Array.from(view.element.querySelectorAll(".ruleview-header"));
+  Assert.deepEqual(
+    headers.map(el => el.textContent),
+    [
+      "Keyframes in-layer",
+      "Keyframes in-starting-style",
+      "Keyframes in-media",
+      "Keyframes in-container",
+    ],
+    "Got expected keyframes sections"
+  );
+
+  info("Check that keyframes' keyframe ancestor rules are not displayed");
+  for (const headerEl of headers) {
+    const keyframeContainerId = headerEl
+      .querySelector("button")
+      .getAttribute("aria-controls");
+    const keyframeContainer = view.element.querySelector(
+      `#${keyframeContainerId}`
+    );
+    ok(
+      !!keyframeContainer,
+      `Got keyframe container for "${headerEl.textContent}"`
+    );
+    is(
+      keyframeContainer.querySelector(".ruleview-rule-ancestor"),
+      null,
+      `ancestor data are not displayed for "${headerEl.textContent}" keyframe rules`
+    );
+  }
+});
diff --git a/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js b/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js
index fcd0302624..d1919c6f36 100644
--- a/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js
+++ b/devtools/client/inspector/rules/test/browser_rules_pseudo-element_01.js
@@ -5,13 +5,16 @@
 
 // Test that pseudoelements are displayed correctly in the rule view
 
-const TEST_URI = URL_ROOT + "doc_pseudoelement.html";
+const TEST_URI = URL_ROOT + "doc_pseudoelement.html?#:~:text=fox";
 const PSEUDO_PREF = "devtools.inspector.show_pseudo_elements";
 
 add_task(async function () {
   await pushPref(PSEUDO_PREF, true);
   await pushPref("dom.customHighlightAPI.enabled", true);
+  await pushPref("dom.text_fragments.enabled", true);
   await pushPref("layout.css.modern-range-pseudos.enabled", true);
+  await pushPref("full-screen-api.transition-duration.enter", "0 0");
+  await pushPref("full-screen-api.transition-duration.leave", "0 0");
 
   await addTab(TEST_URI);
   const { inspector, view } = await openRuleView();
@@ -23,9 +26,11 @@ add_task(async function () {
   await testParagraph(inspector, view);
   await testBody(inspector, view);
   await testList(inspector, view);
-  await testDialogBackdrop(inspector, view);
   await testCustomHighlight(inspector, view);
   await testSlider(inspector, view);
+  await testUrlFragmentTextDirective(inspector, view);
+  // keep this one last as it makes the browser go fullscreen and seem to impact other tests
+  await testBackdrop(inspector, view);
 });
 
 async function testTopLeft(inspector, view) {
@@ -288,13 +293,80 @@ async function testList(inspector, view) {
   assertGutters(view);
 }
 
-async function testDialogBackdrop(inspector, view) {
+async function testBackdrop(inspector, view) {
+  info("Test ::backdrop for dialog element");
   await assertPseudoElementRulesNumbers("dialog", inspector, view, {
     elementRulesNb: 3,
     backdropRules: 1,
   });
 
+  info("Test ::backdrop for popover element");
+  await assertPseudoElementRulesNumbers(
+    "#in-dialog[popover]",
+    inspector,
+    view,
+    {
+      elementRulesNb: 3,
+      backdropRules: 1,
+    }
+  );
+
   assertGutters(view);
+
+  info("Test ::backdrop rules are displayed when elements is fullscreen");
+
+  // Wait for the document being activated, so that
+  // fullscreen request won't be denied.
+  const onTabFocused = SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
+    return ContentTaskUtils.waitForCondition(
+      () => content.browsingContext.isActive && content.document.hasFocus(),
+      "document is active"
+    );
+  });
+  gBrowser.selectedBrowser.focus();
+  await onTabFocused;
+
+  info("Request fullscreen");
+  // Entering fullscreen is triggering an update, wait for it so it doesn't impact
+  // the rest of the test
+  let onInspectorUpdated = view.once("ruleview-refreshed");
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], async () => {
+    const canvas = content.document.querySelector("canvas");
+    canvas.requestFullscreen();
+
+    await ContentTaskUtils.waitForCondition(
+      () => content.document.fullscreenElement === canvas,
+      "canvas is fullscreen"
+    );
+  });
+  await onInspectorUpdated;
+
+  await assertPseudoElementRulesNumbers("canvas", inspector, view, {
+    elementRulesNb: 3,
+    backdropRules: 1,
+  });
+
+  assertGutters(view);
+
+  // Exiting fullscreen is triggering an update, wait for it so it doesn't impact
+  // the rest of the test
+  onInspectorUpdated = view.once("ruleview-refreshed");
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], async () => {
+    content.document.exitFullscreen();
+    await ContentTaskUtils.waitForCondition(
+      () => content.document.fullscreenElement === null,
+      "canvas is no longer fullscreen"
+    );
+  });
+  await onInspectorUpdated;
+
+  info(
+    "Test ::backdrop rules are not displayed when elements are not fullscreen"
+  );
+  await assertPseudoElementRulesNumbers("canvas", inspector, view, {
+    elementRulesNb: 3,
+    backdropRules: 0,
+  });
 }
 
 async function testCustomHighlight(inspector, view) {
@@ -376,6 +448,19 @@ async function testSlider(inspector, view) {
   );
 }
 
+async function testUrlFragmentTextDirective(inspector, view) {
+  await assertPseudoElementRulesNumbers(
+    ".url-fragment-text-directives",
+    inspector,
+    view,
+    {
+      elementRulesNb: 3,
+      targetTextRulesNb: 1,
+    }
+  );
+  assertGutters(view);
+}
+
 function convertTextPropsToString(textProps) {
   return textProps
     .map(
@@ -436,6 +521,9 @@ async function assertPseudoElementRulesNumbers(
     sliderTrackRules: elementStyle.rules.filter(
       rule => rule.pseudoElement === "::slider-track"
     ),
+    targetTextRules: elementStyle.rules.filter(
+      rule => rule.pseudoElement === "::target-text"
+    ),
   };
 
   is(
@@ -493,6 +581,11 @@ async function assertPseudoElementRulesNumbers(
     ruleNbs.sliderTrackRulesNb || 0,
     selector + " has the correct number of ::slider-track rules"
   );
+  is(
+    rules.targetTextRules.length,
+    ruleNbs.targetTextRulesNb || 0,
+    selector + " has the correct number of ::target-text rules"
+  );
 
   // If we do have pseudo element rules displayed, ensure we don't mark their selectors
   // as matched or unmatched
diff --git a/devtools/client/inspector/rules/test/doc_pseudoelement.html b/devtools/client/inspector/rules/test/doc_pseudoelement.html
index 8e077e220b..88611d6633 100644
--- a/devtools/client/inspector/rules/test/doc_pseudoelement.html
+++ b/devtools/client/inspector/rules/test/doc_pseudoelement.html
@@ -110,7 +110,11 @@ p:first-letter {
     color: purple;
 }
 
-dialog::backdrop {
+:is(
+    dialog,
+    [popover],
+    :fullscreen,
+)::backdrop {
     background-color: transparent;
 }
 
@@ -142,6 +146,10 @@ input::slider-thumb {
 input::slider-track {
     background: seagreen;
 }
+
+.url-fragment-text-directives::target-text {
+    background-color: salmon;
+}
     </style>
   </head>
   <body>
@@ -167,7 +175,10 @@ input::slider-track {
         <li id="list" class="box">List element</li>
     </ol>
 
-    <dialog>In dialog</dialog>
+    <dialog>
+        In dialog
+        <div id="in-dialog" popover>hello</div>
+    </dialog>
 
     <label>Range <input type="range" class="slider"></label>
     <label>Not range <input type="text" class="slider"></label>
@@ -177,10 +188,15 @@ input::slider-track {
         You can use them to examine, edit, and debug HTML, CSS, and JavaScript.
     </section>
 
+    <section class="url-fragment-text-directives">May the fox be with you</section>
+
+    <canvas></canvas>
+
     <script>
         "use strict";
         // This is the only way to have the ::backdrop style to be applied
         document.querySelector("dialog").showModal()
+        document.querySelector("#in-dialog").showPopover()
 
         // Register highlights for ::highlight pseudo elements
         const highlightsContainer = document.querySelector(".highlights-container");
diff --git a/devtools/client/inspector/shared/utils.js b/devtools/client/inspector/shared/utils.js
index 542f9897b1..655f143978 100644
--- a/devtools/client/inspector/shared/utils.js
+++ b/devtools/client/inspector/shared/utils.js
@@ -12,7 +12,7 @@ loader.lazyRequireGetter(
 );
 loader.lazyRequireGetter(
   this,
-  "getCSSLexer",
+  "InspectorCSSParserWrapper",
   "resource://devtools/shared/css/lexer.js",
   true
 );
@@ -51,11 +51,11 @@ function advanceValidate(keyCode, value, insertionPoint) {
   // value.  Otherwise it's been inserted in some spot where it has a
   // valid meaning, like a comment or string.
   value = value.slice(0, insertionPoint) + ";" + value.slice(insertionPoint);
-  const lexer = getCSSLexer(value);
+  const lexer = new InspectorCSSParserWrapper(value);
   while (true) {
     const token = lexer.nextToken();
     if (token.endOffset > insertionPoint) {
-      if (token.tokenType === "symbol" && token.text === ";") {
+      if (token.tokenType === "Semicolon") {
         // The ";" is a terminator.
         return true;
       }
diff --git a/devtools/client/inspector/test/browser_inspector_picker-shift-key.js b/devtools/client/inspector/test/browser_inspector_picker-shift-key.js
index 2eb1c04709..db1d5510e7 100644
--- a/devtools/client/inspector/test/browser_inspector_picker-shift-key.js
+++ b/devtools/client/inspector/test/browser_inspector_picker-shift-key.js
@@ -13,12 +13,18 @@ const TEST_URI = `data:text/html;charset=utf-8,
     <div id="nopointer" style="pointer-events: none">Element with pointer-events: none</div>
     <div id="transluscent" style="pointer-events: none;opacity: 0.1">Element with opacity of 0.1</div>
     <div id="invisible" style="pointer-events: none;opacity: 0">Element with opacity of 0</div>
+    <div>
+      <header>Hello</header>
+      <div style="z-index:-1;position:relative;">
+        <span id="negative-z-index-child">ZZ</span>
+      </div>
+    </div>
   </main>`;
 const IS_OSX = Services.appinfo.OS === "Darwin";
 
 add_task(async function () {
-  const { inspector, toolbox } = await openInspectorForURL(TEST_URI);
-
+  const { inspector, toolbox, highlighterTestFront } =
+    await openInspectorForURL(TEST_URI);
   const body = await getNodeFront("body", inspector);
   is(
     inspector.selection.nodeFront,
@@ -72,6 +78,31 @@ add_task(async function () {
     shiftKey: true,
   });
   await checkElementSelected("main", inspector);
+
+  info("Shift-clicking element with negative z-index parent works");
+  await hoverElement(
+    inspector,
+    "#negative-z-index-child",
+    undefined,
+    undefined,
+    {
+      shiftKey: true,
+    }
+  );
+  is(
+    await highlighterTestFront.getHighlighterNodeTextContent(
+      "box-model-infobar-id"
+    ),
+    "#negative-z-index-child",
+    "The highlighter is shown on #negative-z-index-child"
+  );
+
+  await clickElement({
+    inspector,
+    selector: "#negative-z-index-child",
+    shiftKey: true,
+  });
+  await checkElementSelected("#negative-z-index-child", inspector);
 });
 
 async function clickElement({ selector, inspector, shiftKey }) {
diff --git a/devtools/client/inspector/test/head.js b/devtools/client/inspector/test/head.js
index cb1b00030c..73c8902c6b 100644
--- a/devtools/client/inspector/test/head.js
+++ b/devtools/client/inspector/test/head.js
@@ -131,10 +131,12 @@ function pickElement(inspector, selector, x, y) {
  *        X-offset from the top-left corner of the element matching the provided selector
  * @param {Number} y
  *        Y-offset from the top-left corner of the element matching the provided selector
+ * @param {Object} eventOptions
+ *        Options that will be passed to synthesizeMouse
  * @return {Promise} promise that resolves when both the "picker-node-hovered" and
  *                   "highlighter-shown" events are emitted.
  */
-async function hoverElement(inspector, selector, x, y) {
+async function hoverElement(inspector, selector, x, y, eventOptions = {}) {
   const { waitForHighlighterTypeShown } = getHighlighterTestHelpers(inspector);
   info(`Waiting for element "${selector}" to be hovered`);
   const onHovered = inspector.toolbox.nodePicker.once("picker-node-hovered");
@@ -159,7 +161,7 @@ async function hoverElement(inspector, selector, x, y) {
   if (isNaN(x) || isNaN(y)) {
     BrowserTestUtils.synthesizeMouseAtCenter(
       selector,
-      { type: "mousemove" },
+      { ...eventOptions, type: "mousemove" },
       browsingContext
     );
   } else {
@@ -167,7 +169,7 @@ async function hoverElement(inspector, selector, x, y) {
       selector,
       x,
       y,
-      { type: "mousemove" },
+      { ...eventOptions, type: "mousemove" },
       browsingContext
     );
   }
diff --git a/devtools/client/netmonitor/test/browser.toml b/devtools/client/netmonitor/test/browser.toml
index 186810de06..52f465ab57 100644
--- a/devtools/client/netmonitor/test/browser.toml
+++ b/devtools/client/netmonitor/test/browser.toml
@@ -12,6 +12,7 @@ support-files = [
   "html_cause-test-page.html",
   "html_content-type-without-cache-test-page.html",
   "html_brotli-test-page.html",
+  "html_zstd-test-page.html",
   "html_image-tooltip-test-page.html",
   "html_cache-test-page.html",
   "html_cors-test-page.html",
@@ -49,6 +50,7 @@ support-files = [
   "html_single-get-page.html",
   "html_slow-requests-test-page.html",
   "html_send-beacon.html",
+  "html_send-beacon-late-iframe-request.html",
   "html_sorting-test-page.html",
   "html_statistics-edge-case-page.html",
   "html_statistics-test-page.html",
@@ -557,3 +559,5 @@ fail-if = ["a11y_checks"] # Bug 1849028 clicked element may not be focusable and
 ["browser_net_ws-sse-persist-columns.js"]
 
 ["browser_net_ws-stomp-payload.js"]
+
+["browser_net_zstd.js"]
diff --git a/devtools/client/netmonitor/test/browser_net_clear.js b/devtools/client/netmonitor/test/browser_net_clear.js
index 5a97de3e02..e831d07e36 100644
--- a/devtools/client/netmonitor/test/browser_net_clear.js
+++ b/devtools/client/netmonitor/test/browser_net_clear.js
@@ -15,7 +15,7 @@ Services.scriptloader.loadSubScript(
 add_task(async function () {
   Services.prefs.setBoolPref("devtools.webconsole.filter.net", true);
 
-  const { monitor, toolbox } = await initNetMonitor(SIMPLE_URL, {
+  const { monitor, toolbox } = await initNetMonitor(HTTPS_SIMPLE_URL, {
     requestCount: 1,
   });
   info("Starting test... ");
@@ -43,7 +43,7 @@ add_task(async function () {
   await onWebConsole;
 
   info("Wait for request");
-  await waitFor(() => findMessageByType(hud, SIMPLE_URL, ".network"));
+  await waitFor(() => findMessageByType(hud, HTTPS_SIMPLE_URL, ".network"));
 
   info("Switch back the the netmonitor");
   await monitor.toolbox.selectTool("netmonitor");
@@ -63,7 +63,9 @@ add_task(async function () {
 
   info("Wait for network request to show and that its disabled");
 
-  await waitFor(() => findMessageByType(hud, SIMPLE_URL, ".network.disabled"));
+  await waitFor(() =>
+    findMessageByType(hud, HTTPS_SIMPLE_URL, ".network.disabled")
+  );
 
   // Switch back to the netmonitor.
   await monitor.toolbox.selectTool("netmonitor");
diff --git a/devtools/client/netmonitor/test/browser_net_column_slow-request-indicator.js b/devtools/client/netmonitor/test/browser_net_column_slow-request-indicator.js
index 368873c3c6..34dd64ac38 100644
--- a/devtools/client/netmonitor/test/browser_net_column_slow-request-indicator.js
+++ b/devtools/client/netmonitor/test/browser_net_column_slow-request-indicator.js
@@ -12,6 +12,8 @@ add_task(async function () {
   // definately above the slow threshold set here.
   const SLOW_THRESHOLD = 450;
 
+  await pushPref("dom.security.https_first", false);
+
   Services.prefs.setIntPref("devtools.netmonitor.audits.slow", SLOW_THRESHOLD);
 
   const { monitor } = await initNetMonitor(SLOW_REQUESTS_URL, {
diff --git a/devtools/client/netmonitor/test/browser_net_send-beacon.js b/devtools/client/netmonitor/test/browser_net_send-beacon.js
index d47299ca7f..9d1f078bf5 100644
--- a/devtools/client/netmonitor/test/browser_net_send-beacon.js
+++ b/devtools/client/netmonitor/test/browser_net_send-beacon.js
@@ -7,6 +7,8 @@
  * Tests if beacons are handled correctly.
  */
 
+const IFRAME_URL = EXAMPLE_URL + "html_send-beacon-late-iframe-request.html";
+
 add_task(async function () {
   const { tab, monitor } = await initNetMonitor(SEND_BEACON_URL, {
     requestCount: 1,
@@ -40,5 +42,26 @@ add_task(async function () {
   is(request.status, "404", "The status is correct.");
   is(request.blockedReason, 0, "The request is not blocked");
 
+  const onNetworkEvents = waitForNetworkEvents(monitor, 2);
+  await SpecialPowers.spawn(
+    tab.linkedBrowser,
+    [IFRAME_URL],
+    async function (url) {
+      const iframe = content.document.createElement("iframe");
+      iframe.src = url;
+      content.document.body.appendChild(iframe);
+      await new Promise(resolve => (iframe.onload = resolve));
+      iframe.remove();
+    }
+  );
+  await onNetworkEvents;
+
+  // Request at index 1 will be the HTML page of the iframe
+  const lateRequest = getSortedRequests(store.getState())[2];
+  is(lateRequest.method, "POST", "The method is correct.");
+  ok(lateRequest.url.endsWith("beacon_late_request"), "The URL is correct.");
+  is(lateRequest.status, "404", "The status is correct.");
+  is(lateRequest.blockedReason, 0, "The request is not blocked");
+
   return teardown(monitor);
 });
diff --git a/devtools/client/netmonitor/test/browser_net_zstd.js b/devtools/client/netmonitor/test/browser_net_zstd.js
new file mode 100644
index 0000000000..07b6f3a89f
--- /dev/null
+++ b/devtools/client/netmonitor/test/browser_net_zstd.js
@@ -0,0 +1,81 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const ZSTD_URL = HTTPS_EXAMPLE_URL + "html_zstd-test-page.html";
+const ZSTD_REQUESTS = 1;
+
+/**
+ * Test zstd encoded response is handled correctly on HTTPS.
+ */
+
+add_task(async function () {
+  const {
+    L10N,
+  } = require("resource://devtools/client/netmonitor/src/utils/l10n.js");
+
+  const { tab, monitor } = await initNetMonitor(ZSTD_URL, {
+    requestCount: 1,
+  });
+  info("Starting test... ");
+
+  const { document, store, windowRequire } = monitor.panelWin;
+  const Actions = windowRequire("devtools/client/netmonitor/src/actions/index");
+  const { getDisplayedRequests, getSortedRequests } = windowRequire(
+    "devtools/client/netmonitor/src/selectors/index"
+  );
+
+  store.dispatch(Actions.batchEnable(false));
+
+  // Execute requests.
+  await performRequests(monitor, tab, ZSTD_REQUESTS);
+
+  const requestItem = document.querySelector(".request-list-item");
+  // Status code title is generated on hover
+  const requestsListStatus = requestItem.querySelector(".status-code");
+  EventUtils.sendMouseEvent({ type: "mouseover" }, requestsListStatus);
+  await waitUntil(() => requestsListStatus.title);
+  await waitForDOMIfNeeded(requestItem, ".requests-list-timings-total");
+
+  verifyRequestItemTarget(
+    document,
+    getDisplayedRequests(store.getState()),
+    getSortedRequests(store.getState())[0],
+    "GET",
+    HTTPS_CONTENT_TYPE_SJS + "?fmt=zstd",
+    {
+      status: 200,
+      statusText: "OK",
+      type: "json",
+      fullMimeType: "text/json",
+      transferred: L10N.getFormatStrWithNumbers("networkMenu.sizeB", 261),
+      size: L10N.getFormatStrWithNumbers("networkMenu.sizeB", 64),
+      time: true,
+    }
+  );
+
+  const wait = waitForDOM(document, ".CodeMirror-code");
+  const onResponseContent = monitor.panelWin.api.once(
+    TEST_EVENTS.RECEIVED_RESPONSE_CONTENT
+  );
+  store.dispatch(Actions.toggleNetworkDetails());
+  clickOnSidebarTab(document, "response");
+  await wait;
+  await onResponseContent;
+  await testResponse("zstd");
+  await teardown(monitor);
+
+  function testResponse(type) {
+    switch (type) {
+      case "zstd": {
+        is(
+          getCodeMirrorValue(monitor),
+          "X".repeat(64),
+          "The text shown in the source editor is incorrect for the zstd request."
+        );
+        break;
+      }
+    }
+  }
+});
diff --git a/devtools/client/netmonitor/test/html_send-beacon-late-iframe-request.html b/devtools/client/netmonitor/test/html_send-beacon-late-iframe-request.html
new file mode 100644
index 0000000000..3d567bd5d9
--- /dev/null
+++ b/devtools/client/netmonitor/test/html_send-beacon-late-iframe-request.html
@@ -0,0 +1,25 @@
+<!-- Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!doctype html>
+
+<html>
+  <head>
+    <meta charset="utf-8"/>
+    <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
+    <meta http-equiv="Pragma" content="no-cache" />
+    <meta http-equiv="Expires" content="0" />
+    <title>Network Monitor test page</title>
+  </head>
+
+  <body>
+    <p>Do a late beacon request on iframe removal</p>
+
+    <script type="text/javascript">
+    "use strict";
+
+    window.onunload = () => {
+      navigator.sendBeacon("beacon_late_request");
+    };
+    </script>
+  </body>
+</html>
diff --git a/devtools/client/netmonitor/test/html_zstd-test-page.html b/devtools/client/netmonitor/test/html_zstd-test-page.html
new file mode 100644
index 0000000000..52fdabcecb
--- /dev/null
+++ b/devtools/client/netmonitor/test/html_zstd-test-page.html
@@ -0,0 +1,41 @@
+<!-- Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/ -->
+     <!doctype html>
+
+     <html>
+       <head>
+         <meta charset="utf-8"/>
+         <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
+         <meta http-equiv="Pragma" content="no-cache" />
+         <meta http-equiv="Expires" content="0" />
+         <title>Network Monitor test page</title>
+       </head>
+
+       <body>
+         <p>Zstd test</p>
+
+         <script type="text/javascript">
+           /* exported performRequests */
+           "use strict";
+
+           function get(address) {
+             return new Promise(resolve => {
+               const xhr = new XMLHttpRequest();
+               xhr.open("GET", address, true);
+
+               xhr.onreadystatechange = function() {
+                 if (this.readyState == this.DONE) {
+                   resolve();
+                 }
+               };
+               xhr.send(null);
+             });
+           }
+
+           async function performRequests() {
+             await get("sjs_content-type-test-server.sjs?fmt=zstd");
+           }
+         </script>
+       </body>
+
+     </html>
diff --git a/devtools/client/netmonitor/test/sjs_content-type-test-server.sjs b/devtools/client/netmonitor/test/sjs_content-type-test-server.sjs
index d9ac186396..adc882252d 100644
--- a/devtools/client/netmonitor/test/sjs_content-type-test-server.sjs
+++ b/devtools/client/netmonitor/test/sjs_content-type-test-server.sjs
@@ -372,6 +372,18 @@ function handleRequest(request, response) {
           response.finish();
           break;
         }
+        case "zstd": {
+          response.setStatusLine(request.httpVersion, status, "OK");
+          response.setHeader("Content-Type", "text/json", false);
+          response.setHeader("Content-Encoding", "zstd", false);
+          setCacheHeaders();
+          // Use static data since we cannot encode zstandard.
+          const data = "(\xb5/\xfd @E\x00\x00\x10XX\x01\x00\x93\x00\x16";
+          response.setHeader("Content-Length", "" + data.length, false);
+          response.write(data);
+          response.finish();
+          break;
+        }
         case "hls-m3u8": {
           response.setStatusLine(request.httpVersion, status, "OK");
           response.setHeader("Content-Type", "application/x-mpegurl", false);
diff --git a/devtools/client/performance-new/shared/background.sys.mjs b/devtools/client/performance-new/shared/background.sys.mjs
index 4b19f68b71..a110b3e4cb 100644
--- a/devtools/client/performance-new/shared/background.sys.mjs
+++ b/devtools/client/performance-new/shared/background.sys.mjs
@@ -124,7 +124,7 @@ export const presets = {
   "web-developer": {
     entries: 128 * 1024 * 1024,
     interval: 1,
-    features: ["screenshots", "js", "cpu"],
+    features: ["screenshots", "js", "cpu", "memory"],
     threads: ["GeckoMain", "Compositor", "Renderer", "DOM Worker"],
     duration: 0,
     profilerViewMode: "active-tab",
@@ -142,7 +142,15 @@ export const presets = {
   "firefox-platform": {
     entries: 128 * 1024 * 1024,
     interval: 1,
-    features: ["screenshots", "js", "stackwalk", "cpu", "java", "processcpu"],
+    features: [
+      "screenshots",
+      "js",
+      "stackwalk",
+      "cpu",
+      "java",
+      "processcpu",
+      "memory",
+    ],
     threads: [
       "GeckoMain",
       "Compositor",
@@ -165,7 +173,7 @@ export const presets = {
   graphics: {
     entries: 128 * 1024 * 1024,
     interval: 1,
-    features: ["stackwalk", "js", "cpu", "java", "processcpu"],
+    features: ["stackwalk", "js", "cpu", "java", "processcpu", "memory"],
     threads: [
       "GeckoMain",
       "Compositor",
@@ -199,6 +207,7 @@ export const presets = {
       "audiocallbacktracing",
       "ipcmessages",
       "processcpu",
+      "memory",
     ],
     threads: [
       "cubeb",
@@ -248,6 +257,7 @@ export const presets = {
       "java",
       "processcpu",
       "bandwidth",
+      "memory",
     ],
     threads: [
       "Compositor",
@@ -286,6 +296,7 @@ export const presets = {
       "markersallthreads",
       "power",
       "bandwidth",
+      "memory",
     ],
     threads: ["GeckoMain", "Renderer"],
     duration: 0,
@@ -785,12 +796,13 @@ async function getResponseForMessage(request, browser) {
           return profileCaptureResult.profile;
         case "ERROR":
           throw profileCaptureResult.error;
-        default:
+        default: {
           const { UnhandledCaseError } = lazy.Utils();
           throw new UnhandledCaseError(
             profileCaptureResult,
             "profileCaptureResult"
           );
+        }
       }
     }
     case "GET_SYMBOL_TABLE": {
@@ -831,13 +843,14 @@ async function getResponseForMessage(request, browser) {
       }
       return [];
     }
-    default:
+    default: {
       console.error(
         "An unknown message type was received by the profiler's WebChannel handler.",
         request
       );
       const { UnhandledCaseError } = lazy.Utils();
       throw new UnhandledCaseError(request, "WebChannel request");
+    }
   }
 }
 
diff --git a/devtools/client/performance-new/shared/utils.js b/devtools/client/performance-new/shared/utils.js
index ae00b673de..ac98962307 100644
--- a/devtools/client/performance-new/shared/utils.js
+++ b/devtools/client/performance-new/shared/utils.js
@@ -415,6 +415,13 @@ const featureDescriptions = [
     recommended: true,
   },
   {
+    name: "Memory Tracking",
+    value: "memory",
+    title:
+      "Track the memory allocations and deallocations per process over time.",
+    recommended: true,
+  },
+  {
     name: "Java",
     value: "java",
     title: "Profile Java code",
diff --git a/devtools/client/performance-new/test/browser/browser_interaction-between-interfaces.js b/devtools/client/performance-new/test/browser/browser_interaction-between-interfaces.js
index 1268cf818d..6171ed546c 100644
--- a/devtools/client/performance-new/test/browser/browser_interaction-between-interfaces.js
+++ b/devtools/client/performance-new/test/browser/browser_interaction-between-interfaces.js
@@ -294,18 +294,11 @@ add_task(async function test_change_in_about_profiling() {
         "The new value should have the same count of threads as the old value, please double check the test code."
       );
       setThreadInputValue(newThreadValue);
-      checkDevtoolsCustomPresetContent(
-        devtoolsDocument,
-        `
-          Interval: 2 ms
-          Threads: GeckoMain, Dummy
-          JavaScript
-          Native Stacks
-          CPU Utilization
-          Audio Callback Tracing
-          IPC Messages
-          Process CPU Utilization
-        `
+      ok(
+        getDevtoolsCustomPresetContent(devtoolsDocument).includes(
+          "Threads: GeckoMain, Dummy\n"
+        ),
+        "Threads list should match the changed value"
       );
     }
   );
diff --git a/devtools/client/shared/components/object-inspector/utils/node.js b/devtools/client/shared/components/object-inspector/utils/node.js
index 0d049e1c4b..63d358e580 100644
--- a/devtools/client/shared/components/object-inspector/utils/node.js
+++ b/devtools/client/shared/components/object-inspector/utils/node.js
@@ -283,10 +283,7 @@ function nodeHasEntries(item) {
     className === "MIDIInputMap" ||
     className === "MIDIOutputMap" ||
     className === "HighlightRegistry" ||
-    // @backward-compat { version 125 } Support for enumerate CustomStateSet items was
-    // added in 125. When connecting to older server, we don't want to show the <entries>
-    // node for them. The extra check can be removed once 125 hits release.
-    (className === "CustomStateSet" && Array.isArray(value.preview?.items))
+    className === "CustomStateSet"
   );
 }
 
diff --git a/devtools/client/shared/css-angle.js b/devtools/client/shared/css-angle.js
index 903b7813ad..d89cba5b7f 100644
--- a/devtools/client/shared/css-angle.js
+++ b/devtools/client/shared/css-angle.js
@@ -6,7 +6,9 @@
 
 const SPECIALVALUES = new Set(["initial", "inherit", "unset"]);
 
-const { getCSSLexer } = require("resource://devtools/shared/css/lexer.js");
+const {
+  InspectorCSSParserWrapper,
+} = require("resource://devtools/shared/css/lexer.js");
 
 loader.lazyRequireGetter(
   this,
@@ -68,13 +70,14 @@ CssAngle.prototype = {
   },
 
   get valid() {
-    const token = getCSSLexer(this.authored).nextToken();
+    const token = new InspectorCSSParserWrapper(this.authored).nextToken();
     if (!token) {
       return false;
     }
+
     return (
-      token.tokenType === "dimension" &&
-      token.text.toLowerCase() in this.ANGLEUNIT
+      token.tokenType === "Dimension" &&
+      token.unit.toLowerCase() in this.ANGLEUNIT
     );
   },
 
diff --git a/devtools/client/shared/output-parser.js b/devtools/client/shared/output-parser.js
index bd514096b3..5202ae3a8e 100644
--- a/devtools/client/shared/output-parser.js
+++ b/devtools/client/shared/output-parser.js
@@ -8,7 +8,9 @@ const {
   angleUtils,
 } = require("resource://devtools/client/shared/css-angle.js");
 const { colorUtils } = require("resource://devtools/shared/css/color.js");
-const { getCSSLexer } = require("resource://devtools/shared/css/lexer.js");
+const {
+  InspectorCSSParserWrapper,
+} = require("resource://devtools/shared/css/lexer.js");
 const {
   appendText,
 } = require("resource://devtools/client/inspector/shared/utils.js");
@@ -67,6 +69,13 @@ const BACKDROP_FILTER_ENABLED = Services.prefs.getBoolPref(
 );
 const HTML_NS = "http://www.w3.org/1999/xhtml";
 
+// This regexp matches a URL token.  It puts the "url(", any
+// leading whitespace, and any opening quote into |leader|; the
+// URL text itself into |body|, and any trailing quote, trailing
+// whitespace, and the ")" into |trailer|.
+const URL_REGEX =
+  /^(?<leader>url\([ \t\r\n\f]*(["']?))(?<body>.*?)(?<trailer>\2[ \t\r\n\f]*\))$/i;
+
 // Very long text properties should be truncated using CSS to avoid creating
 // extremely tall propertyvalue containers. 5000 characters is an arbitrary
 // limit. Assuming an average ruleview can hold 50 characters per line, this
@@ -175,7 +184,7 @@ class OutputParser {
    * @param  {Boolean} stopAtComma
    *         If true, stop at a comma.
    * @return {Object}
-   *         An object of the form {tokens, functionData, sawComma, sawVariable}.
+   *         An object of the form {tokens, functionData, sawComma, sawVariable, depth}.
    *         |tokens| is a list of the non-comment, non-whitespace tokens
    *         that were seen. The stopping token (paren or comma) will not
    *         be included.
@@ -184,6 +193,7 @@ class OutputParser {
    *         not be included.
    *         |sawComma| is true if the stop was due to a comma, or false otherwise.
    *         |sawVariable| is true if a variable was seen while parsing the text.
+   *         |depth| is the number of unclosed parenthesis remaining when we return.
    */
   #parseMatchingParens(text, tokenStream, options, stopAtComma) {
     let depth = 1;
@@ -196,24 +206,22 @@ class OutputParser {
       if (!token) {
         break;
       }
-      if (token.tokenType === "comment") {
+      if (token.tokenType === "Comment") {
         continue;
       }
 
-      if (token.tokenType === "symbol") {
-        if (stopAtComma && depth === 1 && token.text === ",") {
-          return { tokens, functionData, sawComma: true, sawVariable };
-        } else if (token.text === "(") {
-          ++depth;
-        } else if (token.text === ")") {
-          --depth;
-          if (depth === 0) {
-            break;
-          }
+      if (stopAtComma && depth === 1 && token.tokenType === "Comma") {
+        return { tokens, functionData, sawComma: true, sawVariable, depth };
+      } else if (token.tokenType === "ParenthesisBlock") {
+        ++depth;
+      } else if (token.tokenType === "CloseParenthesis") {
+        --depth;
+        if (depth === 0) {
+          break;
         }
       } else if (
-        token.tokenType === "function" &&
-        token.text === "var" &&
+        token.tokenType === "Function" &&
+        token.value === "var" &&
         options.getVariableValue
       ) {
         sawVariable = true;
@@ -224,24 +232,24 @@ class OutputParser {
           options
         );
         functionData.push({ node, value, fallbackValue });
-      } else if (token.tokenType === "function") {
+      } else if (token.tokenType === "Function") {
         ++depth;
       }
 
       if (
-        token.tokenType !== "function" ||
-        token.text !== "var" ||
+        token.tokenType !== "Function" ||
+        token.value !== "var" ||
         !options.getVariableValue
       ) {
         functionData.push(text.substring(token.startOffset, token.endOffset));
       }
 
-      if (token.tokenType !== "whitespace") {
+      if (token.tokenType !== "WhiteSpace") {
         tokens.push(token);
       }
     }
 
-    return { tokens, functionData, sawComma: false, sawVariable };
+    return { tokens, functionData, sawComma: false, sawVariable, depth };
   }
 
   /**
@@ -389,19 +397,23 @@ class OutputParser {
       }
       const lowerCaseTokenText = token.text?.toLowerCase();
 
-      if (token.tokenType === "comment") {
+      if (token.tokenType === "Comment") {
         // This doesn't change spaceNeeded, because we didn't emit
         // anything to the output.
         continue;
       }
 
       switch (token.tokenType) {
-        case "function": {
-          const isColorTakingFunction =
-            COLOR_TAKING_FUNCTIONS.includes(lowerCaseTokenText);
+        case "Function": {
+          const functionName = token.value;
+          const lowerCaseFunctionName = functionName.toLowerCase();
+
+          const isColorTakingFunction = COLOR_TAKING_FUNCTIONS.includes(
+            lowerCaseFunctionName
+          );
           if (
             isColorTakingFunction ||
-            ANGLE_TAKING_FUNCTIONS.includes(lowerCaseTokenText)
+            ANGLE_TAKING_FUNCTIONS.includes(lowerCaseFunctionName)
           ) {
             // The function can accept a color or an angle argument, and we know
             // it isn't special in some other way. So, we let it
@@ -414,10 +426,13 @@ class OutputParser {
               outerMostFunctionTakesColor = isColorTakingFunction;
             }
             if (isColorTakingFunction) {
-              colorFunctions.push({ parenDepth, functionName: token.text });
+              colorFunctions.push({ parenDepth, functionName });
             }
             ++parenDepth;
-          } else if (lowerCaseTokenText === "var" && options.getVariableValue) {
+          } else if (
+            lowerCaseFunctionName === "var" &&
+            options.getVariableValue
+          ) {
             const { node: variableNode, value } = this.#parseVariable(
               token,
               text,
@@ -434,20 +449,17 @@ class OutputParser {
               this.#parsed.push(variableNode);
             }
           } else {
-            const { functionData, sawVariable } = this.#parseMatchingParens(
-              text,
-              tokenStream,
-              options
-            );
-
-            const functionName = text.substring(
-              token.startOffset,
-              token.endOffset
-            );
+            const {
+              functionData,
+              sawVariable,
+              tokens: functionArgTokens,
+              depth,
+            } = this.#parseMatchingParens(text, tokenStream, options);
 
             if (sawVariable) {
               const computedFunctionText =
                 functionName +
+                "(" +
                 functionData
                   .map(data => {
                     if (typeof data === "string") {
@@ -466,6 +478,7 @@ class OutputParser {
                   colorFunction: colorFunctions.at(-1)?.functionName,
                   valueParts: [
                     functionName,
+                    "(",
                     ...functionData.map(data => data.node || data),
                     ")",
                   ],
@@ -473,7 +486,7 @@ class OutputParser {
               } else {
                 // If function contains variable, we need to add both strings
                 // and nodes.
-                this.#appendTextNode(functionName);
+                this.#appendTextNode(functionName + "(");
                 for (const data of functionData) {
                   if (typeof data === "string") {
                     this.#appendTextNode(data);
@@ -486,16 +499,40 @@ class OutputParser {
             } else {
               // If no variable in function, join the text together and add
               // to DOM accordingly.
-              const functionText = functionName + functionData.join("") + ")";
+              const functionText =
+                functionName +
+                "(" +
+                functionData.join("") +
+                // only append closing parenthesis if the authored text actually had it
+                // In such case, we should probably indicate that there's a "syntax error"
+                // See Bug 1891461.
+                (depth == 0 ? ")" : "");
+
+              if (lowerCaseFunctionName === "url" && options.urlClass) {
+                // url() with quoted strings are not mapped as UnquotedUrl,
+                // instead, we get a "Function" token with "url" function name,
+                // and later, a "QuotedString" token, which contains the actual URL.
+                let url;
+                for (const argToken of functionArgTokens) {
+                  if (argToken.tokenType === "QuotedString") {
+                    url = argToken.value;
+                    break;
+                  }
+                }
 
-              if (
+                if (url !== undefined) {
+                  this.#appendURL(functionText, url, options);
+                } else {
+                  this.#appendTextNode(functionText);
+                }
+              } else if (
                 options.expectCubicBezier &&
-                lowerCaseTokenText === "cubic-bezier"
+                lowerCaseFunctionName === "cubic-bezier"
               ) {
                 this.#appendCubicBezier(functionText, options);
               } else if (
                 options.expectLinearEasing &&
-                lowerCaseTokenText === "linear"
+                lowerCaseFunctionName === "linear"
               ) {
                 this.#appendLinear(functionText, options);
               } else if (
@@ -508,7 +545,7 @@ class OutputParser {
                 });
               } else if (
                 options.expectShape &&
-                BASIC_SHAPE_FUNCTIONS.includes(lowerCaseTokenText)
+                BASIC_SHAPE_FUNCTIONS.includes(lowerCaseFunctionName)
               ) {
                 this.#appendShape(functionText, options);
               } else {
@@ -519,7 +556,7 @@ class OutputParser {
           break;
         }
 
-        case "ident":
+        case "Ident":
           if (
             options.expectCubicBezier &&
             BEZIER_KEYWORDS.includes(lowerCaseTokenText)
@@ -553,8 +590,8 @@ class OutputParser {
           }
           break;
 
-        case "id":
-        case "hash": {
+        case "IDHash":
+        case "Hash": {
           const original = text.substring(token.startOffset, token.endOffset);
           if (colorOK() && InspectorUtils.isValidCSSColor(original)) {
             if (spaceNeeded) {
@@ -571,7 +608,7 @@ class OutputParser {
           }
           break;
         }
-        case "dimension":
+        case "Dimension":
           const value = text.substring(token.startOffset, token.endOffset);
           if (angleOK(value)) {
             this.#appendAngle(value, options);
@@ -579,16 +616,16 @@ class OutputParser {
             this.#appendTextNode(value);
           }
           break;
-        case "url":
-        case "bad_url":
+        case "UnquotedUrl":
+        case "BadUrl":
           this.#appendURL(
             text.substring(token.startOffset, token.endOffset),
-            token.text,
+            token.value,
             options
           );
           break;
 
-        case "string":
+        case "QuotedString":
           if (options.expectFont) {
             fontFamilyNameParts.push(
               text.substring(token.startOffset, token.endOffset)
@@ -600,7 +637,7 @@ class OutputParser {
           }
           break;
 
-        case "whitespace":
+        case "WhiteSpace":
           if (options.expectFont) {
             fontFamilyNameParts.push(" ");
           } else {
@@ -610,32 +647,44 @@ class OutputParser {
           }
           break;
 
-        case "symbol":
-          if (token.text === "(") {
-            ++parenDepth;
-          } else if (token.text === ")") {
-            --parenDepth;
+        case "ParenthesisBlock":
+          ++parenDepth;
+          this.#appendTextNode(
+            text.substring(token.startOffset, token.endOffset)
+          );
+          break;
 
-            if (colorFunctions.at(-1)?.parenDepth == parenDepth) {
-              colorFunctions.pop();
-            }
+        case "CloseParenthesis":
+          --parenDepth;
 
-            if (stopAtCloseParen && parenDepth === 0) {
-              done = true;
-              break;
-            }
+          if (colorFunctions.at(-1)?.parenDepth == parenDepth) {
+            colorFunctions.pop();
+          }
 
-            if (parenDepth === 0) {
-              outerMostFunctionTakesColor = false;
-            }
-          } else if (
-            (token.text === "," || token.text === "!") &&
+          if (stopAtCloseParen && parenDepth === 0) {
+            done = true;
+            break;
+          }
+
+          if (parenDepth === 0) {
+            outerMostFunctionTakesColor = false;
+          }
+          this.#appendTextNode(
+            text.substring(token.startOffset, token.endOffset)
+          );
+          break;
+
+        case "Comma":
+        case "Delim":
+          if (
+            (token.tokenType === "Comma" || token.text === "!") &&
             options.expectFont &&
             fontFamilyNameParts.length !== 0
           ) {
             this.#appendFontFamily(fontFamilyNameParts.join(""), options);
             fontFamilyNameParts = [];
           }
+
         // falls through
         default:
           this.#appendTextNode(
@@ -647,15 +696,15 @@ class OutputParser {
       // If this token might possibly introduce token pasting when
       // color-cycling, require a space.
       spaceNeeded =
-        token.tokenType === "ident" ||
-        token.tokenType === "at" ||
-        token.tokenType === "id" ||
-        token.tokenType === "hash" ||
-        token.tokenType === "number" ||
-        token.tokenType === "dimension" ||
-        token.tokenType === "percentage" ||
-        token.tokenType === "dimension";
-      previousWasBang = token.tokenType === "symbol" && token.text === "!";
+        token.tokenType === "Ident" ||
+        token.tokenType === "AtKeyword" ||
+        token.tokenType === "IDHash" ||
+        token.tokenType === "Hash" ||
+        token.tokenType === "Number" ||
+        token.tokenType === "Dimension" ||
+        token.tokenType === "Percentage" ||
+        token.tokenType === "Dimension";
+      previousWasBang = token.tokenType === "Delim" && token.text === "!";
     }
 
     if (options.expectFont && fontFamilyNameParts.length !== 0) {
@@ -686,7 +735,7 @@ class OutputParser {
     text = text.trim();
     this.#parsed.length = 0;
 
-    const tokenStream = getCSSLexer(text);
+    const tokenStream = new InspectorCSSParserWrapper(text);
     return this.#doParse(text, options, tokenStream, false);
   }
 
@@ -884,7 +933,7 @@ class OutputParser {
    */
   // eslint-disable-next-line complexity
   #addPolygonPointNodes(coords, container) {
-    const tokenStream = getCSSLexer(coords);
+    const tokenStream = new InspectorCSSParserWrapper(coords);
     let token = tokenStream.nextToken();
     let coord = "";
     let i = 0;
@@ -897,7 +946,7 @@ class OutputParser {
     });
 
     while (token) {
-      if (token.tokenType === "symbol" && token.text === ",") {
+      if (token.tokenType === "Comma") {
         // Comma separating coordinate pairs; add coordNode to container and reset vars
         if (!isXCoord) {
           // Y coord not added to coordNode yet
@@ -933,19 +982,19 @@ class OutputParser {
           class: "ruleview-shape-point",
           "data-point": `${i}`,
         });
-      } else if (token.tokenType === "symbol" && token.text === "(") {
+      } else if (token.tokenType === "ParenthesisBlock") {
         depth++;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "symbol" && token.text === ")") {
+      } else if (token.tokenType === "CloseParenthesis") {
         depth--;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "whitespace" && coord === "") {
+      } else if (token.tokenType === "WhiteSpace" && coord === "") {
         // Whitespace at beginning of coord; add to container
         appendText(
           container,
           coords.substring(token.startOffset, token.endOffset)
         );
-      } else if (token.tokenType === "whitespace" && depth === 0) {
+      } else if (token.tokenType === "WhiteSpace" && depth === 0) {
         // Whitespace signifying end of coord
         const node = this.#createNode(
           "span",
@@ -964,10 +1013,10 @@ class OutputParser {
         coord = "";
         isXCoord = !isXCoord;
       } else if (
-        token.tokenType === "number" ||
-        token.tokenType === "dimension" ||
-        token.tokenType === "percentage" ||
-        token.tokenType === "function"
+        token.tokenType === "Number" ||
+        token.tokenType === "Dimension" ||
+        token.tokenType === "Percentage" ||
+        token.tokenType === "Function"
       ) {
         if (isXCoord && coord && depth === 0) {
           // Whitespace is not necessary between x/y coords.
@@ -986,11 +1035,11 @@ class OutputParser {
         }
 
         coord += coords.substring(token.startOffset, token.endOffset);
-        if (token.tokenType === "function") {
+        if (token.tokenType === "Function") {
           depth++;
         }
       } else if (
-        token.tokenType === "ident" &&
+        token.tokenType === "Ident" &&
         (token.text === "nonzero" || token.text === "evenodd")
       ) {
         // A fill-rule (nonzero or evenodd).
@@ -1034,7 +1083,7 @@ class OutputParser {
    */
   // eslint-disable-next-line complexity
   #addCirclePointNodes(coords, container) {
-    const tokenStream = getCSSLexer(coords);
+    const tokenStream = new InspectorCSSParserWrapper(coords);
     let token = tokenStream.nextToken();
     let depth = 0;
     let coord = "";
@@ -1044,20 +1093,20 @@ class OutputParser {
       "data-point": "center",
     });
     while (token) {
-      if (token.tokenType === "symbol" && token.text === "(") {
+      if (token.tokenType === "ParenthesisBlock") {
         depth++;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "symbol" && token.text === ")") {
+      } else if (token.tokenType === "CloseParenthesis") {
         depth--;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "whitespace" && coord === "") {
+      } else if (token.tokenType === "WhiteSpace" && coord === "") {
         // Whitespace at beginning of coord; add to container
         appendText(
           container,
           coords.substring(token.startOffset, token.endOffset)
         );
       } else if (
-        token.tokenType === "whitespace" &&
+        token.tokenType === "WhiteSpace" &&
         point === "radius" &&
         depth === 0
       ) {
@@ -1078,7 +1127,7 @@ class OutputParser {
         point = "cx";
         coord = "";
         depth = 0;
-      } else if (token.tokenType === "whitespace" && depth === 0) {
+      } else if (token.tokenType === "WhiteSpace" && depth === 0) {
         // Whitespace signifying end of cx/cy
         const node = this.#createNode(
           "span",
@@ -1097,7 +1146,7 @@ class OutputParser {
         point = point === "cx" ? "cy" : "cx";
         coord = "";
         depth = 0;
-      } else if (token.tokenType === "ident" && token.text === "at") {
+      } else if (token.tokenType === "Ident" && token.text === "at") {
         // "at"; Add radius to container if not already done so
         if (point === "radius" && coord) {
           const node = this.#createNode(
@@ -1118,10 +1167,10 @@ class OutputParser {
         coord = "";
         depth = 0;
       } else if (
-        token.tokenType === "number" ||
-        token.tokenType === "dimension" ||
-        token.tokenType === "percentage" ||
-        token.tokenType === "function"
+        token.tokenType === "Number" ||
+        token.tokenType === "Dimension" ||
+        token.tokenType === "Percentage" ||
+        token.tokenType === "Function"
       ) {
         if (point === "cx" && coord && depth === 0) {
           // Center coords don't require whitespace between x/y. So if current point is
@@ -1142,7 +1191,7 @@ class OutputParser {
         }
 
         coord += coords.substring(token.startOffset, token.endOffset);
-        if (token.tokenType === "function") {
+        if (token.tokenType === "Function") {
           depth++;
         }
       } else {
@@ -1195,7 +1244,7 @@ class OutputParser {
    */
   // eslint-disable-next-line complexity
   #addEllipsePointNodes(coords, container) {
-    const tokenStream = getCSSLexer(coords);
+    const tokenStream = new InspectorCSSParserWrapper(coords);
     let token = tokenStream.nextToken();
     let depth = 0;
     let coord = "";
@@ -1205,19 +1254,19 @@ class OutputParser {
       "data-point": "center",
     });
     while (token) {
-      if (token.tokenType === "symbol" && token.text === "(") {
+      if (token.tokenType === "ParenthesisBlock") {
         depth++;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "symbol" && token.text === ")") {
+      } else if (token.tokenType === "CloseParenthesis") {
         depth--;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "whitespace" && coord === "") {
+      } else if (token.tokenType === "WhiteSpace" && coord === "") {
         // Whitespace at beginning of coord; add to container
         appendText(
           container,
           coords.substring(token.startOffset, token.endOffset)
         );
-      } else if (token.tokenType === "whitespace" && depth === 0) {
+      } else if (token.tokenType === "WhiteSpace" && depth === 0) {
         if (point === "rx" || point === "ry") {
           // Whitespace signifying end of rx/ry
           const node = this.#createNode(
@@ -1256,7 +1305,7 @@ class OutputParser {
           coord = "";
           depth = 0;
         }
-      } else if (token.tokenType === "ident" && token.text === "at") {
+      } else if (token.tokenType === "Ident" && token.text === "at") {
         // "at"; Add radius to container if not already done so
         if (point === "ry" && coord) {
           const node = this.#createNode(
@@ -1277,10 +1326,10 @@ class OutputParser {
         coord = "";
         depth = 0;
       } else if (
-        token.tokenType === "number" ||
-        token.tokenType === "dimension" ||
-        token.tokenType === "percentage" ||
-        token.tokenType === "function"
+        token.tokenType === "Number" ||
+        token.tokenType === "Dimension" ||
+        token.tokenType === "Percentage" ||
+        token.tokenType === "Function"
       ) {
         if (point === "rx" && coord && depth === 0) {
           // Radius coords don't require whitespace between x/y.
@@ -1313,7 +1362,7 @@ class OutputParser {
         }
 
         coord += coords.substring(token.startOffset, token.endOffset);
-        if (token.tokenType === "function") {
+        if (token.tokenType === "Function") {
           depth++;
         }
       } else {
@@ -1366,7 +1415,7 @@ class OutputParser {
   // eslint-disable-next-line complexity
   #addInsetPointNodes(coords, container) {
     const insetPoints = ["top", "right", "bottom", "left"];
-    const tokenStream = getCSSLexer(coords);
+    const tokenStream = new InspectorCSSParserWrapper(coords);
     let token = tokenStream.nextToken();
     let depth = 0;
     let coord = "";
@@ -1383,16 +1432,16 @@ class OutputParser {
       if (round) {
         // Everything that comes after "round" should just be plain text
         otherText[i].push(coords.substring(token.startOffset, token.endOffset));
-      } else if (token.tokenType === "symbol" && token.text === "(") {
+      } else if (token.tokenType === "ParenthesisBlock") {
         depth++;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "symbol" && token.text === ")") {
+      } else if (token.tokenType === "CloseParenthesis") {
         depth--;
         coord += coords.substring(token.startOffset, token.endOffset);
-      } else if (token.tokenType === "whitespace" && coord === "") {
+      } else if (token.tokenType === "WhiteSpace" && coord === "") {
         // Whitespace at beginning of coord; add to container
         otherText[i].push(coords.substring(token.startOffset, token.endOffset));
-      } else if (token.tokenType === "whitespace" && depth === 0) {
+      } else if (token.tokenType === "WhiteSpace" && depth === 0) {
         // Whitespace signifying end of coord; create node and push to nodes
         const node = this.#createNode(
           "span",
@@ -1407,10 +1456,10 @@ class OutputParser {
         otherText[i] = [coords.substring(token.startOffset, token.endOffset)];
         depth = 0;
       } else if (
-        token.tokenType === "number" ||
-        token.tokenType === "dimension" ||
-        token.tokenType === "percentage" ||
-        token.tokenType === "function"
+        token.tokenType === "Number" ||
+        token.tokenType === "Dimension" ||
+        token.tokenType === "Percentage" ||
+        token.tokenType === "Function"
       ) {
         if (coord && depth === 0) {
           // Inset coords don't require whitespace between each coord.
@@ -1428,10 +1477,10 @@ class OutputParser {
         }
 
         coord += coords.substring(token.startOffset, token.endOffset);
-        if (token.tokenType === "function") {
+        if (token.tokenType === "Function") {
           depth++;
         }
-      } else if (token.tokenType === "ident" && token.text === "round") {
+      } else if (token.tokenType === "Ident" && token.text === "round") {
         if (coord && depth === 0) {
           // Whitespace is not necessary before "round"; create a new node for the coord
           const node = this.#createNode(
@@ -1730,13 +1779,15 @@ class OutputParser {
    */
   #sanitizeURL(url) {
     // Re-lex the URL and add any needed termination characters.
-    const urlTokenizer = getCSSLexer(url);
+    const urlTokenizer = new InspectorCSSParserWrapper(url, {
+      trackEOFChars: true,
+    });
     // Just read until EOF; there will only be a single token.
     while (urlTokenizer.nextToken()) {
       // Nothing.
     }
 
-    return urlTokenizer.performEOFFixup(url, true);
+    return urlTokenizer.performEOFFixup(url);
   }
 
   /**
@@ -1756,14 +1807,7 @@ class OutputParser {
       // leave the termination characters.  This isn't strictly
       // "as-authored", but it makes a bit more sense.
       match = this.#sanitizeURL(match);
-      // This regexp matches a URL token.  It puts the "url(", any
-      // leading whitespace, and any opening quote into |leader|; the
-      // URL text itself into |body|, and any trailing quote, trailing
-      // whitespace, and the ")" into |trailer|.  We considered adding
-      // functionality for this to CSSLexer, in some way, but this
-      // seemed simpler on the whole.
-      const urlParts =
-        /^(url\([ \t\r\n\f]*(["']?))(.*?)(\2[ \t\r\n\f]*\))$/i.exec(match);
+      const urlParts = URL_REGEX.exec(match);
 
       // Bail out if that didn't match anything.
       if (!urlParts) {
@@ -1771,7 +1815,7 @@ class OutputParser {
         return;
       }
 
-      const [, leader, , body, trailer] = urlParts;
+      const { leader, body, trailer } = urlParts.groups;
 
       this.#appendTextNode(leader);
 
diff --git a/devtools/client/shared/screenshot.js b/devtools/client/shared/screenshot.js
index ca746f66e7..4031708293 100644
--- a/devtools/client/shared/screenshot.js
+++ b/devtools/client/shared/screenshot.js
@@ -327,9 +327,9 @@ function saveToClipboard(base64URI) {
 let _outputDirectory = null;
 
 /**
- * Returns the default directory for screenshots.
- * If a specific directory for screenshots is not defined,
- * it falls back to the system downloads directory.
+ * Returns the default directory for DevTools screenshots.
+ * For consistency with the Firefox Screenshots feature, this will default to
+ * the preferred downloads directory.
  *
  * @return {Promise<String>} Resolves the path as a string
  */
@@ -338,13 +338,7 @@ async function getOutputDirectory() {
     return _outputDirectory;
   }
 
-  try {
-    // This will throw if there is not a screenshot directory set for the platform
-    _outputDirectory = Services.dirsvc.get("Scrnshts", Ci.nsIFile).path;
-  } catch (e) {
-    _outputDirectory = await lazy.Downloads.getPreferredDownloadsDirectory();
-  }
-
+  _outputDirectory = await lazy.Downloads.getPreferredDownloadsDirectory();
   return _outputDirectory;
 }
 
diff --git a/devtools/client/shared/sourceeditor/css-autocompleter.js b/devtools/client/shared/sourceeditor/css-autocompleter.js
index 7db3cbbc0f..4266bd02b8 100644
--- a/devtools/client/shared/sourceeditor/css-autocompleter.js
+++ b/devtools/client/shared/sourceeditor/css-autocompleter.js
@@ -28,15 +28,14 @@ const {
  * The file 'css-parsing-utils' helps to convert the CSS into meaningful tokens,
  * each having a certain type associated with it. These tokens help us to figure
  * out the currently edited word and to write a CSS state machine to figure out
- * what the user is currently editing. By that, I mean, whether he is editing a
- * selector or a property or a value, or even fine grained information like an
- * id in the selector.
+ * what the user is currently editing (e.g. a selector or a property or a value,
+ * or even fine grained information like an id in the selector).
  *
  * The `resolveState` method iterated over the tokens spitted out by the
  * tokenizer, using switch cases, follows a state machine logic and finally
  * figures out these informations:
  *  - The state of the CSS at the cursor (one out of CSS_STATES)
- *  - The current token that is being edited `cmpleting`
+ *  - The current token that is being edited `completing`
  *  - If the state is "selector", the selector state (one of SELECTOR_STATES)
  *  - If the state is "selector", the current selector till the cursor
  *  - If the state is "value", the corresponding property name
@@ -214,30 +213,26 @@ CSSCompleter.prototype = {
           // From CSS_STATES.property, we can either go to CSS_STATES.value
           // state when we hit the first ':' or CSS_STATES.selector if "}" is
           // reached.
-          if (token.tokenType === "symbol") {
-            switch (token.text) {
-              case ":":
-                scopeStack.push(":");
-                if (tokens[cursor - 2].tokenType != "whitespace") {
-                  propertyName = tokens[cursor - 2].text;
-                } else {
-                  propertyName = tokens[cursor - 3].text;
-                }
-                _state = CSS_STATES.value;
-                break;
+          if (token.tokenType === "Colon") {
+            scopeStack.push(":");
+            if (tokens[cursor - 2].tokenType != "WhiteSpace") {
+              propertyName = tokens[cursor - 2].text;
+            } else {
+              propertyName = tokens[cursor - 3].text;
+            }
+            _state = CSS_STATES.value;
+          }
 
-              case "}":
-                if (/[{f]/.test(peek(scopeStack))) {
-                  const popped = scopeStack.pop();
-                  if (popped == "f") {
-                    _state = CSS_STATES.frame;
-                  } else {
-                    selector = "";
-                    selectors = [];
-                    _state = CSS_STATES.null;
-                  }
-                }
-                break;
+          if (token.tokenType === "CloseCurlyBracket") {
+            if (/[{f]/.test(peek(scopeStack))) {
+              const popped = scopeStack.pop();
+              if (popped == "f") {
+                _state = CSS_STATES.frame;
+              } else {
+                selector = "";
+                selectors = [];
+                _state = CSS_STATES.null;
+              }
             }
           }
           break;
@@ -245,31 +240,27 @@ CSSCompleter.prototype = {
         case CSS_STATES.value:
           // From CSS_STATES.value, we can go to one of CSS_STATES.property,
           // CSS_STATES.frame, CSS_STATES.selector and CSS_STATES.null
-          if (token.tokenType === "symbol") {
-            switch (token.text) {
-              case ";":
-                if (/[:]/.test(peek(scopeStack))) {
-                  scopeStack.pop();
-                  _state = CSS_STATES.property;
-                }
-                break;
+          if (token.tokenType === "Semicolon") {
+            if (/[:]/.test(peek(scopeStack))) {
+              scopeStack.pop();
+              _state = CSS_STATES.property;
+            }
+          }
 
-              case "}":
-                if (peek(scopeStack) == ":") {
-                  scopeStack.pop();
-                }
+          if (token.tokenType === "CloseCurlyBracket") {
+            if (peek(scopeStack) == ":") {
+              scopeStack.pop();
+            }
 
-                if (/[{f]/.test(peek(scopeStack))) {
-                  const popped = scopeStack.pop();
-                  if (popped == "f") {
-                    _state = CSS_STATES.frame;
-                  } else {
-                    selector = "";
-                    selectors = [];
-                    _state = CSS_STATES.null;
-                  }
-                }
-                break;
+            if (/[{f]/.test(peek(scopeStack))) {
+              const popped = scopeStack.pop();
+              if (popped == "f") {
+                _state = CSS_STATES.frame;
+              } else {
+                selector = "";
+                selectors = [];
+                _state = CSS_STATES.null;
+              }
             }
           }
           break;
@@ -277,7 +268,7 @@ CSSCompleter.prototype = {
         case CSS_STATES.selector:
           // From CSS_STATES.selector, we can only go to CSS_STATES.property
           // when we hit "{"
-          if (token.tokenType === "symbol" && token.text == "{") {
+          if (token.tokenType === "CurlyBracketBlock") {
             scopeStack.push("{");
             _state = CSS_STATES.property;
             selectors.push(selector);
@@ -290,74 +281,87 @@ CSSCompleter.prototype = {
             case SELECTOR_STATES.class:
             case SELECTOR_STATES.tag:
               switch (token.tokenType) {
-                case "hash":
-                case "id":
+                case "Hash":
+                case "IDHash":
                   selectorState = SELECTOR_STATES.id;
-                  selector += "#" + token.text;
+                  selector += token.text;
                   break;
 
-                case "symbol":
+                case "Delim":
                   if (token.text == ".") {
                     selectorState = SELECTOR_STATES.class;
                     selector += ".";
                     if (
                       cursor <= tokIndex &&
-                      tokens[cursor].tokenType == "ident"
+                      tokens[cursor].tokenType == "Ident"
                     ) {
                       token = tokens[cursor++];
                       selector += token.text;
                     }
                   } else if (token.text == "#") {
+                    // Lonely # char, that doesn't produce a Hash nor IDHash
                     selectorState = SELECTOR_STATES.id;
                     selector += "#";
-                  } else if (/[>~+]/.test(token.text)) {
+                  } else if (
+                    token.text == "+" ||
+                    token.text == "~" ||
+                    token.text == ">"
+                  ) {
                     selectorState = SELECTOR_STATES.null;
                     selector += token.text;
-                  } else if (token.text == ",") {
-                    selectorState = SELECTOR_STATES.null;
-                    selectors.push(selector);
-                    selector = "";
-                  } else if (token.text == ":") {
-                    selectorState = SELECTOR_STATES.pseudo;
-                    selector += ":";
-                    if (cursor > tokIndex) {
-                      break;
-                    }
+                  }
+                  break;
 
-                    token = tokens[cursor++];
-                    switch (token.tokenType) {
-                      case "function":
-                        if (token.text == "not") {
-                          selectorBeforeNot = selector;
-                          selector = "";
-                          scopeStack.push("(");
-                        } else {
-                          selector += token.text + "(";
-                        }
-                        selectorState = SELECTOR_STATES.null;
-                        break;
-
-                      case "ident":
+                case "Comma":
+                  selectorState = SELECTOR_STATES.null;
+                  selectors.push(selector);
+                  selector = "";
+                  break;
+
+                case "Colon":
+                  selectorState = SELECTOR_STATES.pseudo;
+                  selector += ":";
+                  if (cursor > tokIndex) {
+                    break;
+                  }
+
+                  token = tokens[cursor++];
+                  switch (token.tokenType) {
+                    case "Function":
+                      if (token.value == "not") {
+                        selectorBeforeNot = selector;
+                        selector = "";
+                        scopeStack.push("(");
+                      } else {
                         selector += token.text;
-                        break;
-                    }
-                  } else if (token.text == "[") {
-                    selectorState = SELECTOR_STATES.attribute;
-                    scopeStack.push("[");
-                    selector += "[";
-                  } else if (token.text == ")") {
-                    if (peek(scopeStack) == "(") {
-                      scopeStack.pop();
-                      selector = selectorBeforeNot + "not(" + selector + ")";
-                      selectorBeforeNot = null;
-                    } else {
-                      selector += ")";
-                    }
-                    selectorState = SELECTOR_STATES.null;
+                      }
+                      selectorState = SELECTOR_STATES.null;
+                      break;
+
+                    case "Ident":
+                      selector += token.text;
+                      break;
+                  }
+                  break;
+
+                case "SquareBracketBlock":
+                  selectorState = SELECTOR_STATES.attribute;
+                  scopeStack.push("[");
+                  selector += "[";
+                  break;
+
+                case "CloseParenthesis":
+                  if (peek(scopeStack) == "(") {
+                    scopeStack.pop();
+                    selector = selectorBeforeNot + "not(" + selector + ")";
+                    selectorBeforeNot = null;
+                  } else {
+                    selector += ")";
                   }
+                  selectorState = SELECTOR_STATES.null;
                   break;
 
-                case "whitespace":
+                case "WhiteSpace":
                   selectorState = SELECTOR_STATES.null;
                   selector && (selector += " ");
                   break;
@@ -369,81 +373,94 @@ CSSCompleter.prototype = {
               // SELECTOR_STATES.id, SELECTOR_STATES.class or
               // SELECTOR_STATES.tag
               switch (token.tokenType) {
-                case "hash":
-                case "id":
+                case "Hash":
+                case "IDHash":
                   selectorState = SELECTOR_STATES.id;
-                  selector += "#" + token.text;
+                  selector += token.text;
                   break;
 
-                case "ident":
+                case "Ident":
                   selectorState = SELECTOR_STATES.tag;
                   selector += token.text;
                   break;
 
-                case "symbol":
+                case "Delim":
                   if (token.text == ".") {
                     selectorState = SELECTOR_STATES.class;
                     selector += ".";
                     if (
                       cursor <= tokIndex &&
-                      tokens[cursor].tokenType == "ident"
+                      tokens[cursor].tokenType == "Ident"
                     ) {
                       token = tokens[cursor++];
                       selector += token.text;
                     }
                   } else if (token.text == "#") {
+                    // Lonely # char, that doesn't produce a Hash nor IDHash
                     selectorState = SELECTOR_STATES.id;
                     selector += "#";
                   } else if (token.text == "*") {
                     selectorState = SELECTOR_STATES.tag;
                     selector += "*";
-                  } else if (/[>~+]/.test(token.text)) {
+                  } else if (
+                    token.text == "+" ||
+                    token.text == "~" ||
+                    token.text == ">"
+                  ) {
                     selector += token.text;
-                  } else if (token.text == ",") {
-                    selectorState = SELECTOR_STATES.null;
-                    selectors.push(selector);
-                    selector = "";
-                  } else if (token.text == ":") {
-                    selectorState = SELECTOR_STATES.pseudo;
-                    selector += ":";
-                    if (cursor > tokIndex) {
-                      break;
-                    }
+                  }
+                  break;
 
-                    token = tokens[cursor++];
-                    switch (token.tokenType) {
-                      case "function":
-                        if (token.text == "not") {
-                          selectorBeforeNot = selector;
-                          selector = "";
-                          scopeStack.push("(");
-                        } else {
-                          selector += token.text + "(";
-                        }
-                        selectorState = SELECTOR_STATES.null;
-                        break;
-
-                      case "ident":
+                case "Comma":
+                  selectorState = SELECTOR_STATES.null;
+                  selectors.push(selector);
+                  selector = "";
+                  break;
+
+                case "Colon":
+                  selectorState = SELECTOR_STATES.pseudo;
+                  selector += ":";
+                  if (cursor > tokIndex) {
+                    break;
+                  }
+
+                  token = tokens[cursor++];
+                  switch (token.tokenType) {
+                    case "Function":
+                      if (token.value == "not") {
+                        selectorBeforeNot = selector;
+                        selector = "";
+                        scopeStack.push("(");
+                      } else {
                         selector += token.text;
-                        break;
-                    }
-                  } else if (token.text == "[") {
-                    selectorState = SELECTOR_STATES.attribute;
-                    scopeStack.push("[");
-                    selector += "[";
-                  } else if (token.text == ")") {
-                    if (peek(scopeStack) == "(") {
-                      scopeStack.pop();
-                      selector = selectorBeforeNot + "not(" + selector + ")";
-                      selectorBeforeNot = null;
-                    } else {
-                      selector += ")";
-                    }
-                    selectorState = SELECTOR_STATES.null;
+                      }
+                      selectorState = SELECTOR_STATES.null;
+                      break;
+
+                    case "Ident":
+                      selector += token.text;
+                      break;
                   }
                   break;
 
-                case "whitespace":
+                case "SquareBracketBlock":
+                  selectorState = SELECTOR_STATES.attribute;
+                  scopeStack.push("[");
+                  selector += "[";
+                  break;
+
+                case "CloseParenthesis":
+                  if (peek(scopeStack) == "(") {
+                    scopeStack.pop();
+                    selector = selectorBeforeNot + "not(" + selector + ")";
+                    selectorBeforeNot = null;
+                  } else {
+                    selector += ")";
+                  }
+                  selectorState = SELECTOR_STATES.null;
+                  break;
+
+                case "WhiteSpace":
                   selector && (selector += " ");
                   break;
               }
@@ -451,46 +468,55 @@ CSSCompleter.prototype = {
 
             case SELECTOR_STATES.pseudo:
               switch (token.tokenType) {
-                case "symbol":
-                  if (/[>~+]/.test(token.text)) {
+                case "Delim":
+                  if (
+                    token.text == "+" ||
+                    token.text == "~" ||
+                    token.text == ">"
+                  ) {
                     selectorState = SELECTOR_STATES.null;
                     selector += token.text;
-                  } else if (token.text == ",") {
-                    selectorState = SELECTOR_STATES.null;
-                    selectors.push(selector);
-                    selector = "";
-                  } else if (token.text == ":") {
-                    selectorState = SELECTOR_STATES.pseudo;
-                    selector += ":";
-                    if (cursor > tokIndex) {
-                      break;
-                    }
+                  }
+                  break;
+
+                case "Comma":
+                  selectorState = SELECTOR_STATES.null;
+                  selectors.push(selector);
+                  selector = "";
+                  break;
+
+                case "Colon":
+                  selectorState = SELECTOR_STATES.pseudo;
+                  selector += ":";
+                  if (cursor > tokIndex) {
+                    break;
+                  }
 
-                    token = tokens[cursor++];
-                    switch (token.tokenType) {
-                      case "function":
-                        if (token.text == "not") {
-                          selectorBeforeNot = selector;
-                          selector = "";
-                          scopeStack.push("(");
-                        } else {
-                          selector += token.text + "(";
-                        }
-                        selectorState = SELECTOR_STATES.null;
-                        break;
-
-                      case "ident":
+                  token = tokens[cursor++];
+                  switch (token.tokenType) {
+                    case "Function":
+                      if (token.value == "not") {
+                        selectorBeforeNot = selector;
+                        selector = "";
+                        scopeStack.push("(");
+                      } else {
                         selector += token.text;
-                        break;
-                    }
-                  } else if (token.text == "[") {
-                    selectorState = SELECTOR_STATES.attribute;
-                    scopeStack.push("[");
-                    selector += "[";
+                      }
+                      selectorState = SELECTOR_STATES.null;
+                      break;
+
+                    case "Ident":
+                      selector += token.text;
+                      break;
                   }
                   break;
+                case "SquareBracketBlock":
+                  selectorState = SELECTOR_STATES.attribute;
+                  scopeStack.push("[");
+                  selector += "[";
+                  break;
 
-                case "whitespace":
+                case "WhiteSpace":
                   selectorState = SELECTOR_STATES.null;
                   selector && (selector += " ");
                   break;
@@ -499,29 +525,40 @@ CSSCompleter.prototype = {
 
             case SELECTOR_STATES.attribute:
               switch (token.tokenType) {
-                case "symbol":
-                  if (/[~|^$*]/.test(token.text)) {
-                    selector += token.text;
-                    token = tokens[cursor++];
-                  } else if (token.text == "=") {
+                case "IncludeMatch":
+                case "DashMatch":
+                case "PrefixMatch":
+                case "IncludeSuffixMatchMatch":
+                case "SubstringMatch":
+                  selector += token.text;
+                  token = tokens[cursor++];
+                  break;
+
+                case "Delim":
+                  if (token.text == "=") {
                     selectorState = SELECTOR_STATES.value;
                     selector += token.text;
-                  } else if (token.text == "]") {
-                    if (peek(scopeStack) == "[") {
-                      scopeStack.pop();
-                    }
+                  }
+                  break;
 
-                    selectorState = SELECTOR_STATES.null;
-                    selector += "]";
+                case "CloseSquareBracket":
+                  if (peek(scopeStack) == "[") {
+                    scopeStack.pop();
                   }
+
+                  selectorState = SELECTOR_STATES.null;
+                  selector += "]";
                   break;
 
-                case "ident":
-                case "string":
+                case "Ident":
                   selector += token.text;
                   break;
 
-                case "whitespace":
+                case "QuotedString":
+                  selector += token.value;
+                  break;
+
+                case "WhiteSpace":
                   selector && (selector += " ");
                   break;
               }
@@ -529,23 +566,24 @@ CSSCompleter.prototype = {
 
             case SELECTOR_STATES.value:
               switch (token.tokenType) {
-                case "string":
-                case "ident":
+                case "Ident":
                   selector += token.text;
                   break;
 
-                case "symbol":
-                  if (token.text == "]") {
-                    if (peek(scopeStack) == "[") {
-                      scopeStack.pop();
-                    }
+                case "QuotedString":
+                  selector += token.value;
+                  break;
 
-                    selectorState = SELECTOR_STATES.null;
-                    selector += "]";
+                case "CloseSquareBracket":
+                  if (peek(scopeStack) == "[") {
+                    scopeStack.pop();
                   }
+
+                  selectorState = SELECTOR_STATES.null;
+                  selector += "]";
                   break;
 
-                case "whitespace":
+                case "WhiteSpace":
                   selector && (selector += " ");
                   break;
               }
@@ -557,29 +595,30 @@ CSSCompleter.prototype = {
           // From CSS_STATES.null state, we can go to either CSS_STATES.media or
           // CSS_STATES.selector.
           switch (token.tokenType) {
-            case "hash":
-            case "id":
+            case "Hash":
+            case "IDHash":
               selectorState = SELECTOR_STATES.id;
-              selector = "#" + token.text;
+              selector = token.text;
               _state = CSS_STATES.selector;
               break;
 
-            case "ident":
+            case "Ident":
               selectorState = SELECTOR_STATES.tag;
               selector = token.text;
               _state = CSS_STATES.selector;
               break;
 
-            case "symbol":
+            case "Delim":
               if (token.text == ".") {
                 selectorState = SELECTOR_STATES.class;
                 selector = ".";
                 _state = CSS_STATES.selector;
-                if (cursor <= tokIndex && tokens[cursor].tokenType == "ident") {
+                if (cursor <= tokIndex && tokens[cursor].tokenType == "Ident") {
                   token = tokens[cursor++];
                   selector += token.text;
                 }
               } else if (token.text == "#") {
+                // Lonely # char, that doesn't produce a Hash nor IDHash
                 selectorState = SELECTOR_STATES.id;
                 selector = "#";
                 _state = CSS_STATES.selector;
@@ -587,45 +626,52 @@ CSSCompleter.prototype = {
                 selectorState = SELECTOR_STATES.tag;
                 selector = "*";
                 _state = CSS_STATES.selector;
-              } else if (token.text == ":") {
-                _state = CSS_STATES.selector;
-                selectorState = SELECTOR_STATES.pseudo;
-                selector += ":";
-                if (cursor > tokIndex) {
-                  break;
-                }
+              }
+              break;
 
-                token = tokens[cursor++];
-                switch (token.tokenType) {
-                  case "function":
-                    if (token.text == "not") {
-                      selectorBeforeNot = selector;
-                      selector = "";
-                      scopeStack.push("(");
-                    } else {
-                      selector += token.text + "(";
-                    }
-                    selectorState = SELECTOR_STATES.null;
-                    break;
+            case "Colon":
+              _state = CSS_STATES.selector;
+              selectorState = SELECTOR_STATES.pseudo;
+              selector += ":";
+              if (cursor > tokIndex) {
+                break;
+              }
 
-                  case "ident":
+              token = tokens[cursor++];
+              switch (token.tokenType) {
+                case "Function":
+                  if (token.value == "not") {
+                    selectorBeforeNot = selector;
+                    selector = "";
+                    scopeStack.push("(");
+                  } else {
                     selector += token.text;
-                    break;
-                }
-              } else if (token.text == "[") {
-                _state = CSS_STATES.selector;
-                selectorState = SELECTOR_STATES.attribute;
-                scopeStack.push("[");
-                selector += "[";
-              } else if (token.text == "}") {
-                if (peek(scopeStack) == "@m") {
-                  scopeStack.pop();
-                }
+                  }
+                  selectorState = SELECTOR_STATES.null;
+                  break;
+
+                case "Ident":
+                  selector += token.text;
+                  break;
+              }
+              break;
+
+            case "CloseSquareBracket":
+              _state = CSS_STATES.selector;
+              selectorState = SELECTOR_STATES.attribute;
+              scopeStack.push("[");
+              selector += "[";
+              break;
+
+            case "CurlyBracketBlock":
+              if (peek(scopeStack) == "@m") {
+                scopeStack.pop();
               }
               break;
 
-            case "at":
-              _state = token.text.startsWith("m")
+            case "AtKeyword":
+              // XXX: We should probably handle other at-rules (@container, @property, …)
+              _state = token.value.startsWith("m")
                 ? CSS_STATES.media
                 : CSS_STATES.keyframes;
               break;
@@ -635,7 +681,7 @@ CSSCompleter.prototype = {
         case CSS_STATES.media:
           // From CSS_STATES.media, we can only go to CSS_STATES.null state when
           // we hit the first '{'
-          if (token.tokenType == "symbol" && token.text == "{") {
+          if (token.tokenType == "CurlyBracketBlock") {
             scopeStack.push("@m");
             _state = CSS_STATES.null;
           }
@@ -644,7 +690,7 @@ CSSCompleter.prototype = {
         case CSS_STATES.keyframes:
           // From CSS_STATES.keyframes, we can only go to CSS_STATES.frame state
           // when we hit the first '{'
-          if (token.tokenType == "symbol" && token.text == "{") {
+          if (token.tokenType == "CurlyBracketBlock") {
             scopeStack.push("@k");
             _state = CSS_STATES.frame;
           }
@@ -654,17 +700,15 @@ CSSCompleter.prototype = {
           // From CSS_STATES.frame, we can either go to CSS_STATES.property
           // state when we hit the first '{' or to CSS_STATES.selector when we
           // hit '}'
-          if (token.tokenType == "symbol") {
-            if (token.text == "{") {
-              scopeStack.push("f");
-              _state = CSS_STATES.property;
-            } else if (token.text == "}") {
-              if (peek(scopeStack) == "@k") {
-                scopeStack.pop();
-              }
-
-              _state = CSS_STATES.null;
+          if (token.tokenType == "CurlyBracketBlock") {
+            scopeStack.push("f");
+            _state = CSS_STATES.property;
+          } else if (token.tokenType == "CloseCurlyBracket") {
+            if (peek(scopeStack) == "@k") {
+              scopeStack.pop();
             }
+
+            _state = CSS_STATES.null;
           }
           break;
       }
@@ -688,6 +732,8 @@ CSSCompleter.prototype = {
         this.nullStates.push([tokenLine, tokenCh, [...scopeStack]]);
       }
     }
+    // ^ while loop end
+
     this.state = _state;
     this.propertyName = _state == CSS_STATES.value ? propertyName : null;
     this.selectorState = _state == CSS_STATES.selector ? selectorState : null;
@@ -701,10 +747,18 @@ CSSCompleter.prototype = {
     }
     this.selectors = selectors;
 
-    if (token && token.tokenType != "whitespace") {
+    if (token && token.tokenType != "WhiteSpace") {
       let text;
-      if (token.tokenType == "dimension" || !token.text) {
+      if (token.tokenType == "Dimension" || !token.text) {
         text = source.substring(token.startOffset, token.endOffset);
+      } else if (
+        token.tokenType === "IDHash" ||
+        token.tokenType === "Hash" ||
+        token.tokenType === "AtKeyword" ||
+        token.tokenType === "Function" ||
+        token.tokenType === "QuotedString"
+      ) {
+        text = token.value;
       } else {
         text = token.text;
       }
@@ -1047,10 +1101,10 @@ CSSCompleter.prototype = {
         }
 
         let prevToken = undefined;
-        const tokens = cssTokenizer(lineText);
+        const tokensIterator = cssTokenizer(lineText);
         let found = false;
         const ech = line == caret.line ? caret.ch : 0;
-        for (let token of tokens) {
+        for (let token of tokensIterator) {
           // If the line is completely spaces, handle it differently
           if (lineText.trim() == "") {
             limitedSource += lineText;
@@ -1061,8 +1115,8 @@ CSSCompleter.prototype = {
             );
           }
 
-          // Whitespace cannot change state.
-          if (token.tokenType == "whitespace") {
+          // WhiteSpace cannot change state.
+          if (token.tokenType == "WhiteSpace") {
             prevToken = token;
             continue;
           }
@@ -1072,7 +1126,7 @@ CSSCompleter.prototype = {
             ch: token.endOffset + ech,
           });
           if (check(forwState)) {
-            if (prevToken && prevToken.tokenType == "whitespace") {
+            if (prevToken && prevToken.tokenType == "WhiteSpace") {
               token = prevToken;
             }
             location = {
@@ -1123,8 +1177,8 @@ CSSCompleter.prototype = {
             limitedSource = limitedSource.slice(0, -1 * length);
           }
 
-          // Whitespace cannot change state.
-          if (token.tokenType == "whitespace") {
+          // WhiteSpace cannot change state.
+          if (token.tokenType == "WhiteSpace") {
             continue;
           }
 
@@ -1133,7 +1187,7 @@ CSSCompleter.prototype = {
             ch: token.startOffset,
           });
           if (check(backState)) {
-            if (tokens[i + 1] && tokens[i + 1].tokenType == "whitespace") {
+            if (tokens[i + 1] && tokens[i + 1].tokenType == "WhiteSpace") {
               token = tokens[i + 1];
             }
             location = {
diff --git a/devtools/client/shared/sourceeditor/editor.js b/devtools/client/shared/sourceeditor/editor.js
index 3487acffa4..90e9f6e373 100644
--- a/devtools/client/shared/sourceeditor/editor.js
+++ b/devtools/client/shared/sourceeditor/editor.js
@@ -168,6 +168,7 @@ class Editor extends EventEmitter {
   #win;
   #lineGutterMarkers = new Map();
   #lineContentMarkers = new Map();
+  #lineContentEventHandlers = {};
 
   #updateListener = null;
 
@@ -676,7 +677,9 @@ class Editor extends EventEmitter {
         }
       }),
       lineNumberMarkersCompartment.of([]),
-      lineContentMarkerCompartment.of(this.#lineContentMarkersExtension([])),
+      lineContentMarkerCompartment.of(
+        this.#lineContentMarkersExtension({ markers: [] })
+      ),
       // keep last so other extension take precedence
       codemirror.minimalSetup,
     ];
@@ -696,29 +699,51 @@ class Editor extends EventEmitter {
   /**
    * This creates the extension used to manage the rendering of markers
    * for in editor line content.
-   * @param   {Array}             markers                    - The current list of markers
+   * @param   {Array}             markers - The current list of markers
+   * @param   {Object}            domEventHandlers - A dictionary of handlers for the DOM events
+   *                                                  See https://codemirror.net/docs/ref/#view.PluginSpec.eventHandlers
    * @returns {Array<ViewPlugin>} showLineContentDecorations - An extension which is an array containing the view
    *                                                           which manages the rendering of the line content markers.
    */
-  #lineContentMarkersExtension(markers) {
+  #lineContentMarkersExtension({ markers, domEventHandlers }) {
     const {
-      codemirrorView: { Decoration, ViewPlugin },
-      codemirrorState: { RangeSetBuilder },
+      codemirrorView: { Decoration, ViewPlugin, WidgetType },
+      codemirrorState: { RangeSetBuilder, RangeSet },
     } = this.#CodeMirror6;
 
+    class LineContentWidget extends WidgetType {
+      constructor(line, createElementNode) {
+        super();
+        this.toDOM = () => createElementNode(line);
+      }
+    }
+
     // Build and return the decoration set
     function buildDecorations(view) {
+      if (!markers) {
+        return RangeSet.empty;
+      }
       const builder = new RangeSetBuilder();
       for (const { from, to } of view.visibleRanges) {
         for (let pos = from; pos <= to; ) {
           const line = view.state.doc.lineAt(pos);
-          for (const { lineClassName, condition } of markers) {
-            if (condition(line.number)) {
-              builder.add(
-                line.from,
-                line.from,
-                Decoration.line({ class: lineClassName })
-              );
+          for (const marker of markers) {
+            if (marker.condition(line.number)) {
+              if (marker.lineClassName) {
+                const classDecoration = Decoration.line({
+                  class: marker.lineClassName,
+                });
+                builder.add(line.from, line.from, classDecoration);
+              }
+              if (marker.createLineElementNode) {
+                const nodeDecoration = Decoration.widget({
+                  widget: new LineContentWidget(
+                    line.number,
+                    marker.createLineElementNode
+                  ),
+                });
+                builder.add(line.to, line.to, nodeDecoration);
+              }
             }
           }
           pos = line.to + 1;
@@ -727,9 +752,9 @@ class Editor extends EventEmitter {
       return builder.finish();
     }
 
-    // The view which handles rendering and updating the
+    // The view which handles events, rendering and updating the
     // markers decorations
-    const showLineContentDecorations = ViewPlugin.fromClass(
+    const lineContentMarkersView = ViewPlugin.fromClass(
       class {
         decorations;
         constructor(view) {
@@ -741,10 +766,46 @@ class Editor extends EventEmitter {
           }
         }
       },
-      { decorations: v => v.decorations }
+      {
+        decorations: v => v.decorations,
+        eventHandlers: domEventHandlers || this.#lineContentEventHandlers,
+      }
     );
 
-    return [showLineContentDecorations];
+    return [lineContentMarkersView];
+  }
+
+  /**
+   *
+   * @param {Object} domEventHandlers - A dictionary of handlers for the DOM events
+   */
+  setContentEventListeners(domEventHandlers) {
+    const cm = editors.get(this);
+
+    for (const eventName in domEventHandlers) {
+      const handler = domEventHandlers[eventName];
+      domEventHandlers[eventName] = (event, editor) => {
+        // Wait a cycle so the codemirror updates to the current cursor position,
+        // information, TODO: Currently noticed this issue with CM6, not ideal but should
+        // investigate further Bug 1890895.
+        event.target.ownerGlobal.setTimeout(() => {
+          const view = editor.viewState;
+          const head = view.state.selection.main.head;
+          const cursor = view.state.doc.lineAt(head);
+          const column = head - cursor.from;
+          handler(event, view, cursor.number, column);
+        }, 0);
+      };
+    }
+
+    // Cache the handlers related to the editor content
+    this.#lineContentEventHandlers = domEventHandlers;
+
+    cm.dispatch({
+      effects: this.#compartments.lineContentMarkerCompartment.reconfigure(
+        this.#lineContentMarkersExtension({ domEventHandlers })
+      ),
+    });
   }
 
   /**
@@ -754,6 +815,9 @@ class Editor extends EventEmitter {
    *   @property {string}     marker.lineClassName - The css class to add to the line
    *   @property {function}   marker.condition - The condition that decides if the marker/class gets added or removed.
    *                                             The line is passed as an argument.
+   *   @property {function}   marker.createLineElementNode - This should return the DOM element which
+   *                                            is used for the marker. The line number is passed as a parameter.
+   *                                            This is optional.
    */
   setLineContentMarker(marker) {
     const cm = editors.get(this);
@@ -761,9 +825,9 @@ class Editor extends EventEmitter {
 
     cm.dispatch({
       effects: this.#compartments.lineContentMarkerCompartment.reconfigure(
-        this.#lineContentMarkersExtension(
-          Array.from(this.#lineContentMarkers.values())
-        )
+        this.#lineContentMarkersExtension({
+          markers: Array.from(this.#lineContentMarkers.values()),
+        })
       ),
     });
   }
@@ -778,9 +842,9 @@ class Editor extends EventEmitter {
 
     cm.dispatch({
       effects: this.#compartments.lineContentMarkerCompartment.reconfigure(
-        this.#lineContentMarkersExtension(
-          Array.from(this.#lineContentMarkers.values())
-        )
+        this.#lineContentMarkersExtension({
+          markers: Array.from(this.#lineContentMarkers.values()),
+        })
       ),
     });
   }
@@ -869,31 +933,31 @@ class Editor extends EventEmitter {
     // (representing the lines in the current viewport) and generate a new rangeset for updating the line gutter
     // based on the conditions defined in the markers(for each line) provided.
     const builder = new RangeSetBuilder();
-    for (const { from, to } of cm.visibleRanges) {
-      for (let pos = from; pos <= to; ) {
-        const line = cm.state.doc.lineAt(pos);
-        for (const {
-          lineClassName,
-          condition,
-          createLineElementNode,
-        } of markers) {
-          if (typeof condition !== "function") {
-            throw new Error("The `condition` is not a valid function");
-          }
-          if (condition(line.number)) {
-            builder.add(
-              line.from,
-              line.to,
-              new LineGutterMarker(
-                lineClassName,
-                line.number,
-                createLineElementNode
-              )
-            );
-          }
+    const { from, to } = cm.viewport;
+    let pos = from;
+    while (pos <= to) {
+      const line = cm.state.doc.lineAt(pos);
+      for (const {
+        lineClassName,
+        condition,
+        createLineElementNode,
+      } of markers) {
+        if (typeof condition !== "function") {
+          throw new Error("The `condition` is not a valid function");
+        }
+        if (condition(line.number)) {
+          builder.add(
+            line.from,
+            line.to,
+            new LineGutterMarker(
+              lineClassName,
+              line.number,
+              createLineElementNode
+            )
+          );
         }
-        pos = line.to + 1;
       }
+      pos = line.to + 1;
     }
 
     // To update the state with the newly generated marker range set, a dispatch is called on the view
@@ -907,6 +971,61 @@ class Editor extends EventEmitter {
   }
 
   /**
+   * Gets the position information for the current selection
+   * @returns {Object} cursor      - The location information for the  current selection
+   *                   cursor.from - An object with the starting line / column of the selection
+   *                   cursor.to   - An object with the end line / column of the selection
+   */
+  getSelectionCursor() {
+    const cm = editors.get(this);
+    if (this.config.cm6) {
+      const selection = cm.state.selection.ranges[0];
+      const lineFrom = cm.state.doc.lineAt(selection.from);
+      const lineTo = cm.state.doc.lineAt(selection.to);
+      return {
+        from: {
+          line: lineFrom.number,
+          ch: selection.from - lineFrom.from,
+        },
+        to: {
+          line: lineTo.number,
+          ch: selection.to - lineTo.from,
+        },
+      };
+    }
+    return {
+      from: cm.getCursor("from"),
+      to: cm.getCursor("to"),
+    };
+  }
+
+  /**
+   * Gets the text content for the current selection
+   * @returns {String}
+   */
+  getSelectedText() {
+    const cm = editors.get(this);
+    if (this.config.cm6) {
+      const selection = cm.state.selection.ranges[0];
+      return cm.state.doc.sliceString(selection.from, selection.to);
+    }
+    return cm.getSelection().trim();
+  }
+
+  /**
+   * Check that text is selected
+   * @returns {Boolean}
+   */
+  isTextSelected() {
+    const cm = editors.get(this);
+    if (this.config.cm6) {
+      const selection = cm.state.selection.ranges[0];
+      return selection.from !== selection.to;
+    }
+    return cm.somethingSelected();
+  }
+
+  /**
    * Returns a boolean indicating whether the editor is ready to
    * use. Use appendTo(el).then(() => {}) for most cases
    */
@@ -1860,6 +1979,119 @@ class Editor extends EventEmitter {
   }
 
   /**
+   * This checks if the specified position (top/left) is within the current viewpport
+   * bounds. it helps determine is scrolling should happen.
+   * @param {Object} cm - The codemirror instance
+   * @param {Number} line - The line in the source
+   * @param {Number} column - The column in the source
+   * @returns {Boolean}
+   */
+  #isVisible(cm, line, column) {
+    let inXView, inYView;
+
+    function withinBounds(x, min, max) {
+      return x >= min && x <= max;
+    }
+
+    if (this.config.cm6) {
+      const pos = this.#posToOffset(cm.state.doc, line, column);
+      const coords = pos && cm.coordsAtPos(pos);
+      if (!coords) {
+        return false;
+      }
+      const { scrollTop, scrollLeft, clientHeight, clientWidth } = cm.scrollDOM;
+
+      inXView = withinBounds(coords.left, scrollLeft, scrollLeft + clientWidth);
+      inYView = withinBounds(coords.top, scrollTop, scrollTop + clientHeight);
+    } else {
+      const { top, left } = cm.charCoords({ line, ch: column }, "local");
+      const scrollArea = cm.getScrollInfo();
+      const charWidth = cm.defaultCharWidth();
+      const fontHeight = cm.defaultTextHeight();
+      const { scrollTop, scrollLeft } = cm.doc;
+
+      inXView = withinBounds(
+        left,
+        scrollLeft,
+        // Note: 30 might relate to the margin on one of the scroll bar elements.
+        // See comment https://github.com/firefox-devtools/debugger/pull/5182#discussion_r163439209
+        scrollLeft + (scrollArea.clientWidth - 30) - charWidth
+      );
+      inYView = withinBounds(
+        top,
+        scrollTop,
+        scrollTop + scrollArea.clientHeight - fontHeight
+      );
+    }
+    return inXView && inYView;
+  }
+
+  /**
+   * Converts  line/col to CM6 offset position
+   * @param {Object} doc - the codemirror document
+   * @param {Number} line - The line in the source
+   * @param {Number} col - The column in the source
+   * @returns {Number}
+   */
+  #posToOffset(doc, line, col) {
+    if (!this.config.cm6) {
+      throw new Error("This function is only compatible with CM6");
+    }
+    try {
+      const offset = doc.line(line);
+      return offset.from + col;
+    } catch (e) {
+      // Line likey does not exist in viewport yet
+      console.warn(e.message);
+    }
+    return null;
+  }
+
+  /**
+   * Scrolls the editor to the specified line and column
+   * @param {Number} line - The line in the source
+   * @param {Number} column - The column in the source
+   */
+  scrollTo(line, column) {
+    const cm = editors.get(this);
+    if (this.config.cm6) {
+      const {
+        codemirrorView: { EditorView },
+      } = this.#CodeMirror6;
+
+      if (!this.#isVisible(cm, line, column)) {
+        const offset = this.#posToOffset(cm.state.doc, line, column);
+        if (!offset) {
+          return;
+        }
+        cm.dispatch({
+          effects: EditorView.scrollIntoView(offset, {
+            x: "nearest",
+            y: "center",
+          }),
+        });
+      }
+    } else {
+      // For all cases where these are on the first line and column,
+      // avoid the possibly slow computation of cursor location on large bundles.
+      if (!line && !column) {
+        cm.scrollTo(0, 0);
+        return;
+      }
+
+      const { top, left } = cm.charCoords({ line, ch: column }, "local");
+
+      if (!this.#isVisible(cm, line, column)) {
+        const scroller = cm.getScrollerElement();
+        const centeredX = Math.max(left - scroller.offsetWidth / 2, 0);
+        const centeredY = Math.max(top - scroller.offsetHeight / 2, 0);
+
+        cm.scrollTo(centeredX, centeredY);
+      }
+    }
+  }
+
+  /**
    * Extends an instance of the Editor object with additional
    * functions. Each function will be called with context as
    * the first argument. Context is a {ed, cm} object where
@@ -1901,6 +2133,8 @@ class Editor extends EventEmitter {
     this.#ownerDoc = null;
     this.#updateListener = null;
     this.#lineGutterMarkers.clear();
+    this.#lineContentMarkers.clear();
+    this.#lineContentEventHandlers = {};
 
     if (this.#prefObserver) {
       this.#prefObserver.off(KEYMAP_PREF, this.setKeyMap);
diff --git a/devtools/client/shared/test/browser_filter-editor-01.js b/devtools/client/shared/test/browser_filter-editor-01.js
index 557a02857c..106f89dbc4 100644
--- a/devtools/client/shared/test/browser_filter-editor-01.js
+++ b/devtools/client/shared/test/browser_filter-editor-01.js
@@ -10,15 +10,14 @@ const {
 } = require("resource://devtools/client/shared/widgets/FilterWidget.js");
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
-const { getCSSLexer } = require("resource://devtools/shared/css/lexer.js");
 
 // Verify that the given string consists of a valid CSS URL token.
 // Return true on success, false on error.
 function verifyURL(string) {
-  const lexer = getCSSLexer(string);
+  const lexer = new InspectorCSSParser(string);
 
   const token = lexer.nextToken();
-  if (!token || token.tokenType !== "url") {
+  if (!token || token.tokenType !== "UnquotedUrl") {
     return false;
   }
 
diff --git a/devtools/client/shared/test/browser_outputparser.js b/devtools/client/shared/test/browser_outputparser.js
index 7e0c1b7e00..a2fcce8f78 100644
--- a/devtools/client/shared/test/browser_outputparser.js
+++ b/devtools/client/shared/test/browser_outputparser.js
@@ -700,6 +700,22 @@ function testParseVariable(doc, parser) {
           ")</span>" +
         "</span>",
     },
+    {
+      text: "rgb(var(--not-seen), 0, 0)",
+      variables: {},
+      expected:
+        // prettier-ignore
+        `rgb(` +
+          `<span>` +
+            `var(` +
+              `<span class="unmatched-class" data-variable="--not-seen is not set">` +
+                `--not-seen` +
+              `</span>` +
+            `)` +
+          `</span>` +
+          `, 0, 0` +
+        `)`,
+    },
   ];
 
   for (const test of TESTS) {
diff --git a/devtools/client/shared/test/xpcshell/test_parseDeclarations.js b/devtools/client/shared/test/xpcshell/test_parseDeclarations.js
index 593087d46b..373d5acc56 100644
--- a/devtools/client/shared/test/xpcshell/test_parseDeclarations.js
+++ b/devtools/client/shared/test/xpcshell/test_parseDeclarations.js
@@ -750,7 +750,7 @@ const TEST_DATA = [
     expected: [
       {
         name: "color",
-        value: "blue \\9 no_need",
+        value: "blue \\9 no\\_need",
         priority: "",
         offsets: [0, 23],
         declarationText: "color: blue \\9 no\\_need",
@@ -1609,18 +1609,27 @@ function assertOutput(input, actual, expected) {
         "Check that the output item has the expected name, " +
           "value and priority"
       );
-      Assert.equal(expected[i].name, actual[i].name);
-      Assert.equal(expected[i].value, actual[i].value);
-      Assert.equal(expected[i].priority, actual[i].priority);
-      deepEqual(expected[i].offsets, actual[i].offsets);
+      Assert.equal(actual[i].name, expected[i].name, "Expected name");
+      Assert.equal(actual[i].value, expected[i].value, "Expected value");
+      Assert.equal(
+        actual[i].priority,
+        expected[i].priority,
+        "Expected priority"
+      );
+      deepEqual(actual[i].offsets, expected[i].offsets, "Expected offsets");
       if ("commentOffsets" in expected[i]) {
-        deepEqual(expected[i].commentOffsets, actual[i].commentOffsets);
+        deepEqual(
+          actual[i].commentOffsets,
+          expected[i].commentOffsets,
+          "Expected commentOffsets"
+        );
       }
 
       if (expected[i].declarationText) {
         Assert.equal(
           input.substring(expected[i].offsets[0], expected[i].offsets[1]),
-          expected[i].declarationText
+          expected[i].declarationText,
+          "Expected declarationText"
         );
       }
     }
diff --git a/devtools/client/shared/test/xpcshell/test_rewriteDeclarations.js b/devtools/client/shared/test/xpcshell/test_rewriteDeclarations.js
index 228d2dc79d..9842db7c02 100644
--- a/devtools/client/shared/test/xpcshell/test_rewriteDeclarations.js
+++ b/devtools/client/shared/test/xpcshell/test_rewriteDeclarations.js
@@ -483,9 +483,7 @@ const TEST_DATA = [
       enabled: true,
     },
     expected: "something: \\\\;color: red;",
-    // The lexer rewrites the token before we see it.  However this is
-    // so obscure as to be inconsequential.
-    changed: { 0: "\uFFFD\\" },
+    changed: { 0: "\\\\" },
   },
 
   // Termination insertion corner case.
diff --git a/devtools/client/shared/widgets/CubicBezierWidget.js b/devtools/client/shared/widgets/CubicBezierWidget.js
index 39407d4711..df41949df5 100644
--- a/devtools/client/shared/widgets/CubicBezierWidget.js
+++ b/devtools/client/shared/widgets/CubicBezierWidget.js
@@ -31,7 +31,9 @@ const {
   PRESETS,
   DEFAULT_PRESET_CATEGORY,
 } = require("resource://devtools/client/shared/widgets/CubicBezierPresets.js");
-const { getCSSLexer } = require("resource://devtools/shared/css/lexer.js");
+const {
+  InspectorCSSParserWrapper,
+} = require("resource://devtools/shared/css/lexer.js");
 const XHTML_NS = "http://www.w3.org/1999/xhtml";
 
 /**
@@ -918,13 +920,13 @@ function parseTimingFunction(value) {
     return PREDEFINED[value];
   }
 
-  const tokenStream = getCSSLexer(value);
+  const tokenStream = new InspectorCSSParserWrapper(value);
   const getNextToken = () => {
     while (true) {
       const token = tokenStream.nextToken();
       if (
         !token ||
-        (token.tokenType !== "whitespace" && token.tokenType !== "comment")
+        (token.tokenType !== "WhiteSpace" && token.tokenType !== "Comment")
       ) {
         return token;
       }
@@ -932,24 +934,20 @@ function parseTimingFunction(value) {
   };
 
   let token = getNextToken();
-  if (token.tokenType !== "function" || token.text !== "cubic-bezier") {
+  if (token.tokenType !== "Function" || token.value !== "cubic-bezier") {
     return undefined;
   }
 
   const result = [];
   for (let i = 0; i < 4; ++i) {
     token = getNextToken();
-    if (!token || token.tokenType !== "number") {
+    if (!token || token.tokenType !== "Number") {
       return undefined;
     }
     result.push(token.number);
 
     token = getNextToken();
-    if (
-      !token ||
-      token.tokenType !== "symbol" ||
-      token.text !== (i == 3 ? ")" : ",")
-    ) {
+    if (!token || token.tokenType !== (i == 3 ? "CloseParenthesis" : "Comma")) {
       return undefined;
     }
   }
diff --git a/devtools/client/shared/widgets/FilterWidget.js b/devtools/client/shared/widgets/FilterWidget.js
index bb23bdfeca..487cc9ad0b 100644
--- a/devtools/client/shared/widgets/FilterWidget.js
+++ b/devtools/client/shared/widgets/FilterWidget.js
@@ -814,7 +814,7 @@ CSSFilterEditorWidget.prototype = {
       return;
     }
 
-    for (let { name, value, quote } of tokenizeFilterValue(cssValue)) {
+    for (let { name, value } of tokenizeFilterValue(cssValue)) {
       // If the specified value is invalid, replace it with the
       // default.
       if (name !== "url") {
@@ -823,7 +823,7 @@ CSSFilterEditorWidget.prototype = {
         }
       }
 
-      this.add(name, value, quote, true);
+      this.add(name, value, true);
     }
 
     this.emit("updated", this.getCssValue());
@@ -838,9 +838,6 @@ CSSFilterEditorWidget.prototype = {
    * @param {String} value
    *        value of the filter (e.g. 30px, 20%)
    *        If this is |null|, then a default value may be supplied.
-   * @param {String} quote
-   *        For a url filter, the quoting style.  This can be a
-   *        single quote, a double quote, or empty.
    * @return {Number}
    *        The index of the new filter in the current list of filters
    * @param {Boolean}
@@ -848,7 +845,7 @@ CSSFilterEditorWidget.prototype = {
    *        you're calling add in a loop and wait to emit a single event after
    *        the loop yourself, set this parameter to true.
    */
-  add(name, value, quote, noEvent) {
+  add(name, value, noEvent) {
     const def = this._definition(name);
     if (!def) {
       return false;
@@ -868,11 +865,6 @@ CSSFilterEditorWidget.prototype = {
       } else {
         value = def.range[0] + unitLabel;
       }
-
-      if (name === "url") {
-        // Default quote.
-        quote = '"';
-      }
     }
 
     let unit = def.type === "string" ? "" : (/[a-zA-Z%]+/.exec(value) || [])[0];
@@ -894,7 +886,7 @@ CSSFilterEditorWidget.prototype = {
       }
     }
 
-    const index = this.filters.push({ value, unit, name, quote }) - 1;
+    const index = this.filters.push({ value, unit, name }) - 1;
     if (!noEvent) {
       this.emit("updated", this.getCssValue());
     }
@@ -916,22 +908,12 @@ CSSFilterEditorWidget.prototype = {
       return null;
     }
 
-    // Just return the value+unit for non-url functions.
-    if (filter.name !== "url") {
-      return filter.value + filter.unit;
+    // Just return the value url functions.
+    if (filter.name === "url") {
+      return filter.value;
     }
 
-    // url values need to be quoted and escaped.
-    if (filter.quote === "'") {
-      return "'" + filter.value.replace(/\'/g, "\\'") + "'";
-    } else if (filter.quote === '"') {
-      return '"' + filter.value.replace(/\"/g, '\\"') + '"';
-    }
-
-    // Unquoted.  This approach might change the original input -- for
-    // example the original might be over-quoted.  But, this is
-    // correct and probably good enough.
-    return filter.value.replace(/[\\ \t()"']/g, "\\$&");
+    return filter.value + filter.unit;
   },
 
   removeAt(index) {
@@ -1051,27 +1033,34 @@ function tokenizeFilterValue(css) {
   for (const token of cssTokenizer(css)) {
     switch (state) {
       case "initial":
-        if (token.tokenType === "function") {
-          name = token.text;
+        if (token.tokenType === "Function") {
+          name = token.value;
           contents = "";
           state = "function";
           depth = 1;
-        } else if (token.tokenType === "url" || token.tokenType === "bad_url") {
-          // Extract the quoting style from the url.
-          const originalText = css.substring(
-            token.startOffset,
-            token.endOffset
-          );
-          const [, quote] = /^url\([ \t\r\n\f]*(["']?)/i.exec(originalText);
-
-          filters.push({ name: "url", value: token.text.trim(), quote });
+        } else if (
+          token.tokenType === "UnquotedUrl" ||
+          token.tokenType === "BadUrl"
+        ) {
+          const url = token.text
+            .substring(
+              // token text starts with `url(`
+              4,
+              // unquoted url also include the closing parenthesis
+              token.tokenType == "UnquotedUrl"
+                ? token.text.length - 1
+                : undefined
+            )
+            .trim();
+
+          filters.push({ name: "url", value: url });
           // Leave state as "initial" because the URL token includes
           // the trailing close paren.
         }
         break;
 
       case "function":
-        if (token.tokenType === "symbol" && token.text === ")") {
+        if (token.tokenType === "CloseParenthesis") {
           --depth;
           if (depth === 0) {
             filters.push({ name, value: contents.trim() });
@@ -1081,8 +1070,8 @@ function tokenizeFilterValue(css) {
         }
         contents += css.substring(token.startOffset, token.endOffset);
         if (
-          token.tokenType === "function" ||
-          (token.tokenType === "symbol" && token.text === "(")
+          token.tokenType === "Function" ||
+          token.tokenType === "Parenthesis"
         ) {
           ++depth;
         }
diff --git a/devtools/client/shared/widgets/LinearEasingFunctionWidget.js b/devtools/client/shared/widgets/LinearEasingFunctionWidget.js
index e6d2e604df..5ea3b33d15 100644
--- a/devtools/client/shared/widgets/LinearEasingFunctionWidget.js
+++ b/devtools/client/shared/widgets/LinearEasingFunctionWidget.js
@@ -9,7 +9,7 @@
  */
 
 const EventEmitter = require("devtools/shared/event-emitter");
-const { getCSSLexer } = require("devtools/shared/css/lexer");
+const { InspectorCSSParserWrapper } = require("devtools/shared/css/lexer");
 const { throttle } = require("devtools/shared/throttle");
 const XHTML_NS = "http://www.w3.org/1999/xhtml";
 const SVG_NS = "http://www.w3.org/2000/svg";
@@ -578,13 +578,13 @@ class TimingFunctionPreviewWidget {
  */
 function parseTimingFunction(value) {
   value = value.trim();
-  const tokenStream = getCSSLexer(value);
+  const tokenStream = new InspectorCSSParserWrapper(value);
   const getNextToken = () => {
     while (true) {
       const token = tokenStream.nextToken();
       if (
         !token ||
-        (token.tokenType !== "whitespace" && token.tokenType !== "comment")
+        (token.tokenType !== "WhiteSpace" && token.tokenType !== "Comment")
       ) {
         return token;
       }
@@ -592,7 +592,7 @@ function parseTimingFunction(value) {
   };
 
   let token = getNextToken();
-  if (!token || token.tokenType !== "function" || token.text !== "linear") {
+  if (!token || token.tokenType !== "Function" || token.value !== "linear") {
     return undefined;
   }
 
@@ -601,11 +601,11 @@ function parseTimingFunction(value) {
   let largestInput = -Infinity;
 
   while ((token = getNextToken())) {
-    if (token.text === ")") {
+    if (token.tokenType === "CloseParenthesis") {
       break;
     }
 
-    if (token.tokenType === "number") {
+    if (token.tokenType === "Number") {
       // [parsing step 4.1]
       const point = { input: null, output: token.number };
       // [parsing step 4.2]
@@ -614,7 +614,7 @@ function parseTimingFunction(value) {
       // get nextToken to see if there's a linear stop length
       token = getNextToken();
       // [parsing step 4.3]
-      if (token && token.tokenType === "percentage") {
+      if (token && token.tokenType === "Percentage") {
         // [parsing step 4.3.1]
         point.input = Math.max(token.number, largestInput);
         // [parsing step 4.3.2]
@@ -624,7 +624,7 @@ function parseTimingFunction(value) {
         token = getNextToken();
 
         // [parsing step 4.3.3]
-        if (token && token.tokenType === "percentage") {
+        if (token && token.tokenType === "Percentage") {
           // [parsing step 4.3.3.1]
           const extraPoint = { input: null, output: point.output };
           // [parsing step 4.3.3.2]
diff --git a/devtools/client/storage/test/browser.toml b/devtools/client/storage/test/browser.toml
index 28b4b04258..6afcd80bf2 100644
--- a/devtools/client/storage/test/browser.toml
+++ b/devtools/client/storage/test/browser.toml
@@ -39,6 +39,7 @@ support-files = [
   "storage-unsecured-iframe-usercontextid.html",
   "storage-updates.html",
   "head.js",
+  "!/devtools/client/shared/test/highlighter-test-actor.js",
   "!/devtools/client/shared/test/shared-head.js",
   "!/devtools/client/shared/test/telemetry-test-helpers.js",
 ]
diff --git a/devtools/client/themes/images/tool-profiler.svg b/devtools/client/themes/images/tool-profiler.svg
index 44e435001a..1c605751ca 100644
--- a/devtools/client/themes/images/tool-profiler.svg
+++ b/devtools/client/themes/images/tool-profiler.svg
@@ -1,6 +1,6 @@
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16" fill="context-fill" fill-opacity="context-fill-opacity">
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16" fill="context-fill light-dark(black, white)" fill-opacity="context-fill-opacity">
   <path d="M8 0A8 8 0 0 0 .78 11.43a1 1 0 1 0 1.8-.86 5.94 5.94 0 0 1 0-5.17 6 6 0 0 1 10.83 5.17 1 1 0 1 0 1.81.86A7.99 7.99 0 0 0 8 0M10 12a2 2 0 1 1-4 0 2 2 0 0 1 4 0M10.96 6.7a.5.5 0 1 0-.92-.4l-1.7 3.73a2 2 0 0 1 .92.41l1.7-3.73z"/>
 </svg>
diff --git a/devtools/client/webconsole/components/Output/Message.js b/devtools/client/webconsole/components/Output/Message.js
index ee65c8947a..8fed9fd084 100644
--- a/devtools/client/webconsole/components/Output/Message.js
+++ b/devtools/client/webconsole/components/Output/Message.js
@@ -255,6 +255,10 @@ class Message extends Component {
                     JSON.stringify(
                       this.props.message,
                       function (key, value) {
+                        if (key === "targetFront") {
+                          return null;
+                        }
+
                         // The message can hold one or multiple fronts that we need to serialize
                         if (value?.getGrip) {
                           return value.getGrip();
diff --git a/devtools/client/webconsole/test/browser/_browser_console.toml b/devtools/client/webconsole/test/browser/_browser_console.toml
index d3d3d42146..e5530874ab 100644
--- a/devtools/client/webconsole/test/browser/_browser_console.toml
+++ b/devtools/client/webconsole/test/browser/_browser_console.toml
@@ -61,6 +61,9 @@ skip-if = [
 
 ["browser_console_eager_eval.js"]
 
+["browser_console_eager_eval_resolve.js"]
+skip-if = ["verify"]
+
 ["browser_console_enable_network_monitoring.js"]
 skip-if = [
   "verify",
diff --git a/devtools/client/webconsole/test/browser/browser_console_eager_eval_resolve.js b/devtools/client/webconsole/test/browser/browser_console_eager_eval_resolve.js
new file mode 100644
index 0000000000..cc2daa33ea
--- /dev/null
+++ b/devtools/client/webconsole/test/browser/browser_console_eager_eval_resolve.js
@@ -0,0 +1,64 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+// Check evaluating eager-evaluation values.
+const TEST_URI = "data:text/html;charset=utf8,<!DOCTYPE html>";
+
+add_task(async function () {
+  await addTab(TEST_URI);
+
+  await pushPref("devtools.chrome.enabled", true);
+
+  info("Open the Browser Console");
+  const hud = await BrowserConsoleManager.toggleBrowserConsole();
+
+  await executeResolveHookWithSideEffect(hud);
+});
+
+async function executeResolveHookWithSideEffect(hud) {
+  // Services.droppedLinkHandler is implemented with resolve hook, which imports
+  // ContentAreaDropListener.sys.mjs.
+  //
+  // In order to test the resolve hook behavior, ensure the module is not yet
+  // loaded, which ensures the property is not yet resolved.
+  //
+  // NOTE: This test is not compatible with verify mode, given it depends on the
+  //       initial state of the Services object and the module.
+  is(
+    Cu.isESModuleLoaded(
+      "resource://gre/modules/ContentAreaDropListener.sys.mjs"
+    ),
+    false
+  );
+
+  setInputValue(hud, `Services.droppedLinkHandler`);
+
+  await wait(500);
+  // Eager evaluation should fail, due to the side effect in the resolve hook.
+  await waitForEagerEvaluationResult(hud, "");
+
+  setInputValue(hud, "");
+  await wait(500);
+
+  // The property should be resolved when evaluating after the eager evaluation.
+  await executeAndWaitForResultMessage(
+    hud,
+    `Services.droppedLinkHandler;`,
+    "XPCWrappedNative_NoHelper"
+  );
+
+  is(
+    Cu.isESModuleLoaded(
+      "resource://gre/modules/ContentAreaDropListener.sys.mjs"
+    ),
+    true
+  );
+
+  // Eager evaluation should work after the property is resolved.
+  setInputValue(hud, `Services.droppedLinkHandler`);
+  await wait(500);
+  await waitForEagerEvaluationResult(hud, /XPCWrappedNative_NoHelper/);
+}
diff --git a/devtools/client/webconsole/test/browser/browser_jsterm_screenshot_command_file.js b/devtools/client/webconsole/test/browser/browser_jsterm_screenshot_command_file.js
index f872745bbd..09e17594ab 100644
--- a/devtools/client/webconsole/test/browser/browser_jsterm_screenshot_command_file.js
+++ b/devtools/client/webconsole/test/browser/browser_jsterm_screenshot_command_file.js
@@ -97,16 +97,10 @@ add_task(async function () {
   const dayString = date.getDate().toString().padStart(2, "0");
   const expectedDateString = `${date.getFullYear()}-${monthString}-${dayString}`;
 
-  let screenshotDir;
-  try {
-    // This will throw if there is not a screenshot directory set for the platform
-    screenshotDir = Services.dirsvc.get("Scrnshts", Ci.nsIFile).path;
-  } catch (e) {
-    const { Downloads } = ChromeUtils.importESModule(
-      "resource://gre/modules/Downloads.sys.mjs"
-    );
-    screenshotDir = await Downloads.getPreferredDownloadsDirectory();
-  }
+  const { Downloads } = ChromeUtils.importESModule(
+    "resource://gre/modules/Downloads.sys.mjs"
+  );
+  const screenshotDir = await Downloads.getPreferredDownloadsDirectory();
 
   const { renderedDate, filePath } =
     /Saved to (?<filePath>.*Screen Shot (?<renderedDate>\d{4}-\d{2}-\d{2}) at \d{2}.\d{2}.\d{2}\.png)/.exec(