Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 1223 insertions, 0 deletions

diff --git a/parser/html/nsHtml5TreeOperation.cpp b/parser/html/nsHtml5TreeOperation.cpp
new file mode 100644
index 0000000000..eb99869121
--- /dev/null
+++ b/parser/html/nsHtml5TreeOperation.cpp
@@ -0,0 +1,1223 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 sw=2 et tw=78: */
+/* 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/. */
+
+#include "nsHtml5TreeOperation.h"
+#include "mozAutoDocUpdate.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/Likely.h"
+#include "mozilla/dom/Comment.h"
+#include "mozilla/dom/CustomElementRegistry.h"
+#include "mozilla/dom/DocGroup.h"
+#include "mozilla/dom/DocumentFragment.h"
+#include "mozilla/dom/DocumentType.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/LinkStyle.h"
+#include "mozilla/dom/HTMLFormElement.h"
+#include "mozilla/dom/HTMLImageElement.h"
+#include "mozilla/dom/HTMLTemplateElement.h"
+#include "mozilla/dom/MutationObservers.h"
+#include "mozilla/dom/ShadowRoot.h"
+#include "mozilla/dom/Text.h"
+#include "nsAttrName.h"
+#include "nsContentCreatorFunctions.h"
+#include "nsContentUtils.h"
+#include "nsDocElementCreatedNotificationRunner.h"
+#include "nsEscape.h"
+#include "nsGenericHTMLElement.h"
+#include "nsHtml5AutoPauseUpdate.h"
+#include "nsHtml5DocumentMode.h"
+#include "nsHtml5HtmlAttributes.h"
+#include "nsHtml5SVGLoadDispatcher.h"
+#include "nsHtml5TreeBuilder.h"
+#include "nsIDTD.h"
+#include "nsIFormControl.h"
+#include "nsIMutationObserver.h"
+#include "nsINode.h"
+#include "nsIProtocolHandler.h"
+#include "nsIScriptElement.h"
+#include "nsISupportsImpl.h"
+#include "nsIURI.h"
+#include "nsNetUtil.h"
+#include "nsTextNode.h"
+#include "js/ColumnNumber.h"  // JS::ColumnNumberOneOrigin
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+/**
+ * Helper class that opens a notification batch if the current doc
+ * is different from the executor doc.
+ */
+class MOZ_STACK_CLASS nsHtml5OtherDocUpdate {
+ public:
+  nsHtml5OtherDocUpdate(Document* aCurrentDoc, Document* aExecutorDoc) {
+    MOZ_ASSERT(aCurrentDoc, "Node has no doc?");
+    MOZ_ASSERT(aExecutorDoc, "Executor has no doc?");
+    if (MOZ_LIKELY(aCurrentDoc == aExecutorDoc)) {
+      mDocument = nullptr;
+    } else {
+      mDocument = aCurrentDoc;
+      aCurrentDoc->BeginUpdate();
+    }
+  }
+
+  ~nsHtml5OtherDocUpdate() {
+    if (MOZ_UNLIKELY(mDocument)) {
+      mDocument->EndUpdate();
+    }
+  }
+
+ private:
+  RefPtr<Document> mDocument;
+};
+
+nsHtml5TreeOperation::nsHtml5TreeOperation() : mOperation(uninitialized()) {
+  MOZ_COUNT_CTOR(nsHtml5TreeOperation);
+}
+
+nsHtml5TreeOperation::~nsHtml5TreeOperation() {
+  MOZ_COUNT_DTOR(nsHtml5TreeOperation);
+
+  struct TreeOperationMatcher {
+    void operator()(const opAppend& aOperation) {}
+
+    void operator()(const opDetach& aOperation) {}
+
+    void operator()(const opAppendChildrenToNewParent& aOperation) {}
+
+    void operator()(const opFosterParent& aOperation) {}
+
+    void operator()(const opAppendToDocument& aOperation) {}
+
+    void operator()(const opAddAttributes& aOperation) {
+      delete aOperation.mAttributes;
+    }
+
+    void operator()(const nsHtml5DocumentMode& aMode) {}
+
+    void operator()(const opCreateHTMLElement& aOperation) {
+      aOperation.mName->Release();
+      delete aOperation.mAttributes;
+    }
+
+    void operator()(const opCreateSVGElement& aOperation) {
+      aOperation.mName->Release();
+      delete aOperation.mAttributes;
+    }
+
+    void operator()(const opCreateMathMLElement& aOperation) {
+      aOperation.mName->Release();
+      delete aOperation.mAttributes;
+    }
+
+    void operator()(const opSetFormElement& aOperation) {}
+
+    void operator()(const opAppendText& aOperation) {
+      delete[] aOperation.mBuffer;
+    }
+
+    void operator()(const opFosterParentText& aOperation) {
+      delete[] aOperation.mBuffer;
+    }
+
+    void operator()(const opAppendComment& aOperation) {
+      delete[] aOperation.mBuffer;
+    }
+
+    void operator()(const opAppendCommentToDocument& aOperation) {
+      delete[] aOperation.mBuffer;
+    }
+
+    void operator()(const opAppendDoctypeToDocument& aOperation) {
+      aOperation.mName->Release();
+      delete aOperation.mStringPair;
+    }
+
+    void operator()(const opGetDocumentFragmentForTemplate& aOperation) {}
+
+    void operator()(const opSetDocumentFragmentForTemplate& aOperation) {}
+
+    void operator()(const opGetShadowRootFromHost& aOperation) {}
+
+    void operator()(const opGetFosterParent& aOperation) {}
+
+    void operator()(const opMarkAsBroken& aOperation) {}
+
+    void operator()(const opRunScriptThatMayDocumentWriteOrBlock& aOperation) {}
+
+    void operator()(
+        const opRunScriptThatCannotDocumentWriteOrBlock& aOperation) {}
+
+    void operator()(const opPreventScriptExecution& aOperation) {}
+
+    void operator()(const opDoneAddingChildren& aOperation) {}
+
+    void operator()(const opDoneCreatingElement& aOperation) {}
+
+    void operator()(const opUpdateCharsetSource& aOperation) {}
+
+    void operator()(const opCharsetSwitchTo& aOperation) {}
+
+    void operator()(const opUpdateStyleSheet& aOperation) {}
+
+    void operator()(const opProcessOfflineManifest& aOperation) {
+      free(aOperation.mUrl);
+    }
+
+    void operator()(const opMarkMalformedIfScript& aOperation) {}
+
+    void operator()(const opStreamEnded& aOperation) {}
+
+    void operator()(const opSetStyleLineNumber& aOperation) {}
+
+    void operator()(const opSetScriptLineAndColumnNumberAndFreeze& aOperation) {
+    }
+
+    void operator()(const opSvgLoad& aOperation) {}
+
+    void operator()(const opMaybeComplainAboutCharset& aOperation) {}
+
+    void operator()(const opMaybeComplainAboutDeepTree& aOperation) {}
+
+    void operator()(const opAddClass& aOperation) {}
+
+    void operator()(const opAddViewSourceHref& aOperation) {
+      delete[] aOperation.mBuffer;
+    }
+
+    void operator()(const opAddViewSourceBase& aOperation) {
+      delete[] aOperation.mBuffer;
+    }
+
+    void operator()(const opAddErrorType& aOperation) {
+      if (aOperation.mName) {
+        aOperation.mName->Release();
+      }
+      if (aOperation.mOther) {
+        aOperation.mOther->Release();
+      }
+    }
+
+    void operator()(const opAddLineNumberId& aOperation) {}
+
+    void operator()(const opStartLayout& aOperation) {}
+
+    void operator()(const opEnableEncodingMenu& aOperation) {}
+
+    void operator()(const uninitialized& aOperation) {
+      NS_WARNING("Uninitialized tree op.");
+    }
+  };
+
+  mOperation.match(TreeOperationMatcher());
+}
+
+nsresult nsHtml5TreeOperation::AppendTextToTextNode(
+    const char16_t* aBuffer, uint32_t aLength, Text* aTextNode,
+    nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aTextNode, "Got null text node.");
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+  uint32_t oldLength = aTextNode->TextLength();
+  CharacterDataChangeInfo info = {true, oldLength, oldLength, aLength};
+  MutationObservers::NotifyCharacterDataWillChange(aTextNode, info);
+
+  nsresult rv = aTextNode->AppendText(aBuffer, aLength, false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  MutationObservers::NotifyCharacterDataChanged(aTextNode, info);
+  return rv;
+}
+
+nsresult nsHtml5TreeOperation::AppendText(const char16_t* aBuffer,
+                                          uint32_t aLength, nsIContent* aParent,
+                                          nsHtml5DocumentBuilder* aBuilder) {
+  nsresult rv = NS_OK;
+  nsIContent* lastChild = aParent->GetLastChild();
+  if (lastChild && lastChild->IsText()) {
+    nsHtml5OtherDocUpdate update(aParent->OwnerDoc(), aBuilder->GetDocument());
+    return AppendTextToTextNode(aBuffer, aLength, lastChild->GetAsText(),
+                                aBuilder);
+  }
+
+  nsNodeInfoManager* nodeInfoManager = aParent->OwnerDoc()->NodeInfoManager();
+  RefPtr<nsTextNode> text = new (nodeInfoManager) nsTextNode(nodeInfoManager);
+  NS_ASSERTION(text, "Infallible malloc failed?");
+  rv = text->SetText(aBuffer, aLength, false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return Append(text, aParent, aBuilder);
+}
+
+nsresult nsHtml5TreeOperation::Append(nsIContent* aNode, nsIContent* aParent,
+                                      nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+  ErrorResult rv;
+  nsHtml5OtherDocUpdate update(aParent->OwnerDoc(), aBuilder->GetDocument());
+  aParent->AppendChildTo(aNode, false, rv);
+  if (!rv.Failed()) {
+    aNode->SetParserHasNotified();
+    MutationObservers::NotifyContentAppended(aParent, aNode);
+  }
+  return rv.StealNSResult();
+}
+
+nsresult nsHtml5TreeOperation::Append(nsIContent* aNode, nsIContent* aParent,
+                                      FromParser aFromParser,
+                                      nsHtml5DocumentBuilder* aBuilder) {
+  Maybe<nsHtml5AutoPauseUpdate> autoPause;
+  Maybe<AutoCEReaction> autoCEReaction;
+  DocGroup* docGroup = aParent->OwnerDoc()->GetDocGroup();
+  if (docGroup && aFromParser != FROM_PARSER_FRAGMENT) {
+    autoCEReaction.emplace(docGroup->CustomElementReactionsStack(), nullptr);
+  }
+  nsresult rv = Append(aNode, aParent, aBuilder);
+  // Pause the parser only when there are reactions to be invoked to avoid
+  // pausing parsing too aggressive.
+  if (autoCEReaction.isSome() && docGroup &&
+      docGroup->CustomElementReactionsStack()
+          ->IsElementQueuePushedForCurrentRecursionDepth()) {
+    autoPause.emplace(aBuilder);
+  }
+  return rv;
+}
+
+nsresult nsHtml5TreeOperation::AppendToDocument(
+    nsIContent* aNode, nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->GetDocument() == aNode->OwnerDoc());
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+
+  ErrorResult rv;
+  Document* doc = aBuilder->GetDocument();
+  doc->AppendChildTo(aNode, false, rv);
+  if (rv.ErrorCodeIs(NS_ERROR_DOM_HIERARCHY_REQUEST_ERR)) {
+    aNode->SetParserHasNotified();
+    return NS_OK;
+  }
+  if (rv.Failed()) {
+    return rv.StealNSResult();
+  }
+
+  aNode->SetParserHasNotified();
+  MutationObservers::NotifyContentInserted(doc, aNode);
+
+  NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
+               "Someone forgot to block scripts");
+  if (aNode->IsElement()) {
+    nsContentUtils::AddScriptRunner(
+        new nsDocElementCreatedNotificationRunner(doc));
+  }
+  return NS_OK;
+}
+
+static bool IsElementOrTemplateContent(nsINode* aNode) {
+  if (aNode) {
+    if (aNode->IsElement()) {
+      return true;
+    }
+    if (aNode->IsDocumentFragment()) {
+      // Check if the node is a template content.
+      nsIContent* fragHost = aNode->AsDocumentFragment()->GetHost();
+      if (fragHost && fragHost->IsTemplateElement()) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+void nsHtml5TreeOperation::Detach(nsIContent* aNode,
+                                  nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+  nsCOMPtr<nsINode> parent = aNode->GetParentNode();
+  if (parent) {
+    nsHtml5OtherDocUpdate update(parent->OwnerDoc(), aBuilder->GetDocument());
+    parent->RemoveChildNode(aNode, true);
+  }
+}
+
+nsresult nsHtml5TreeOperation::AppendChildrenToNewParent(
+    nsIContent* aNode, nsIContent* aParent, nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+  nsHtml5OtherDocUpdate update(aParent->OwnerDoc(), aBuilder->GetDocument());
+
+  bool didAppend = false;
+  while (aNode->HasChildren()) {
+    nsCOMPtr<nsIContent> child = aNode->GetFirstChild();
+    aNode->RemoveChildNode(child, true);
+
+    ErrorResult rv;
+    aParent->AppendChildTo(child, false, rv);
+    if (rv.Failed()) {
+      return rv.StealNSResult();
+    }
+    didAppend = true;
+  }
+  if (didAppend) {
+    MutationObservers::NotifyContentAppended(aParent, aParent->GetLastChild());
+  }
+  return NS_OK;
+}
+
+nsresult nsHtml5TreeOperation::FosterParent(nsIContent* aNode,
+                                            nsIContent* aParent,
+                                            nsIContent* aTable,
+                                            nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+  nsIContent* foster = aTable->GetParent();
+
+  if (IsElementOrTemplateContent(foster)) {
+    nsHtml5OtherDocUpdate update(foster->OwnerDoc(), aBuilder->GetDocument());
+
+    ErrorResult rv;
+    foster->InsertChildBefore(aNode, aTable, false, rv);
+    if (rv.Failed()) {
+      return rv.StealNSResult();
+    }
+
+    MutationObservers::NotifyContentInserted(foster, aNode);
+    return NS_OK;
+  }
+
+  return Append(aNode, aParent, aBuilder);
+}
+
+nsresult nsHtml5TreeOperation::AddAttributes(nsIContent* aNode,
+                                             nsHtml5HtmlAttributes* aAttributes,
+                                             nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aNode->IsAnyOfHTMLElements(nsGkAtoms::body, nsGkAtoms::html));
+
+  Element* node = aNode->AsElement();
+  nsHtml5OtherDocUpdate update(node->OwnerDoc(), aBuilder->GetDocument());
+
+  int32_t len = aAttributes->getLength();
+  for (int32_t i = len; i > 0;) {
+    --i;
+    nsAtom* localName = aAttributes->getLocalNameNoBoundsCheck(i);
+    int32_t nsuri = aAttributes->getURINoBoundsCheck(i);
+    if (!node->HasAttr(nsuri, localName) &&
+        !(nsuri == kNameSpaceID_None && localName == nsGkAtoms::nonce)) {
+      nsString value;  // Not Auto, because using it to hold nsStringBuffer*
+      aAttributes->getValueNoBoundsCheck(i).ToString(value);
+      node->SetAttr(nsuri, localName, aAttributes->getPrefixNoBoundsCheck(i),
+                    value, true);
+      // XXX what to do with nsresult?
+    }
+  }
+  return NS_OK;
+}
+
+void nsHtml5TreeOperation::SetHTMLElementAttributes(
+    Element* aElement, nsAtom* aName, nsHtml5HtmlAttributes* aAttributes) {
+  int32_t len = aAttributes->getLength();
+  aElement->TryReserveAttributeCount((uint32_t)len);
+  if (aAttributes->getDuplicateAttributeError()) {
+    aElement->SetParserHadDuplicateAttributeError();
+  }
+  for (int32_t i = 0; i < len; i++) {
+    nsHtml5String val = aAttributes->getValueNoBoundsCheck(i);
+    nsAtom* klass = val.MaybeAsAtom();
+    if (klass) {
+      aElement->SetClassAttrFromParser(klass);
+    } else {
+      nsAtom* localName = aAttributes->getLocalNameNoBoundsCheck(i);
+      nsAtom* prefix = aAttributes->getPrefixNoBoundsCheck(i);
+      int32_t nsuri = aAttributes->getURINoBoundsCheck(i);
+      nsString value;  // Not Auto, because using it to hold nsStringBuffer*
+      val.ToString(value);
+      aElement->SetAttr(nsuri, localName, prefix, value, false);
+    }
+  }
+}
+
+nsIContent* nsHtml5TreeOperation::CreateHTMLElement(
+    nsAtom* aName, nsHtml5HtmlAttributes* aAttributes, FromParser aFromParser,
+    nsNodeInfoManager* aNodeInfoManager, nsHtml5DocumentBuilder* aBuilder,
+    HTMLContentCreatorFunction aCreator) {
+  RefPtr<NodeInfo> nodeInfo = aNodeInfoManager->GetNodeInfo(
+      aName, nullptr, kNameSpaceID_XHTML, nsINode::ELEMENT_NODE);
+  NS_ASSERTION(nodeInfo, "Got null nodeinfo.");
+
+  Document* document = nodeInfo->GetDocument();
+  RefPtr<nsAtom> isAtom;
+  if (aAttributes) {
+    nsHtml5String is = aAttributes->getValue(nsHtml5AttributeName::ATTR_IS);
+    if (is) {
+      nsAutoString isValue;
+      is.ToString(isValue);
+      isAtom = NS_Atomize(isValue);
+    }
+  }
+
+  const bool isCustomElement = aCreator == NS_NewCustomElement || isAtom;
+  CustomElementDefinition* customElementDefinition = nullptr;
+  if (isCustomElement && aFromParser != FROM_PARSER_FRAGMENT) {
+    RefPtr<nsAtom> tagAtom = nodeInfo->NameAtom();
+    RefPtr<nsAtom> typeAtom =
+        aCreator == NS_NewCustomElement ? tagAtom : isAtom;
+
+    MOZ_ASSERT(nodeInfo->NameAtom()->Equals(nodeInfo->LocalName()));
+    customElementDefinition = nsContentUtils::LookupCustomElementDefinition(
+        document, nodeInfo->NameAtom(), nodeInfo->NamespaceID(), typeAtom);
+  }
+
+  auto DoCreateElement = [&](HTMLContentCreatorFunction aCreator) -> Element* {
+    nsCOMPtr<Element> newElement;
+    if (aCreator) {
+      newElement = aCreator(nodeInfo.forget(), aFromParser);
+    } else {
+      NS_NewHTMLElement(getter_AddRefs(newElement), nodeInfo.forget(),
+                        aFromParser, isAtom, customElementDefinition);
+    }
+
+    MOZ_ASSERT(newElement, "Element creation created null pointer.");
+    Element* element = newElement.get();
+    aBuilder->HoldElement(newElement.forget());
+
+    if (auto* linkStyle = LinkStyle::FromNode(*element)) {
+      linkStyle->DisableUpdates();
+    }
+
+    if (!aAttributes) {
+      return element;
+    }
+
+    SetHTMLElementAttributes(element, aName, aAttributes);
+    return element;
+  };
+
+  if (customElementDefinition) {
+    // This will cause custom element constructors to run.
+    AutoSetThrowOnDynamicMarkupInsertionCounter
+        throwOnDynamicMarkupInsertionCounter(document);
+    nsHtml5AutoPauseUpdate autoPauseContentUpdate(aBuilder);
+    { nsAutoMicroTask mt; }
+    AutoCEReaction autoCEReaction(
+        document->GetDocGroup()->CustomElementReactionsStack(), nullptr);
+    return DoCreateElement(nullptr);
+  }
+  return DoCreateElement(isCustomElement ? nullptr : aCreator);
+}
+
+nsIContent* nsHtml5TreeOperation::CreateSVGElement(
+    nsAtom* aName, nsHtml5HtmlAttributes* aAttributes, FromParser aFromParser,
+    nsNodeInfoManager* aNodeInfoManager, nsHtml5DocumentBuilder* aBuilder,
+    SVGContentCreatorFunction aCreator) {
+  nsCOMPtr<nsIContent> newElement;
+  if (MOZ_LIKELY(aNodeInfoManager->SVGEnabled())) {
+    RefPtr<NodeInfo> nodeInfo = aNodeInfoManager->GetNodeInfo(
+        aName, nullptr, kNameSpaceID_SVG, nsINode::ELEMENT_NODE);
+    MOZ_ASSERT(nodeInfo, "Got null nodeinfo.");
+
+    DebugOnly<nsresult> rv =
+        aCreator(getter_AddRefs(newElement), nodeInfo.forget(), aFromParser);
+    MOZ_ASSERT(NS_SUCCEEDED(rv) && newElement);
+  } else {
+    RefPtr<NodeInfo> nodeInfo = aNodeInfoManager->GetNodeInfo(
+        aName, nullptr, kNameSpaceID_disabled_SVG, nsINode::ELEMENT_NODE);
+    MOZ_ASSERT(nodeInfo, "Got null nodeinfo.");
+
+    // The mismatch between NS_NewXMLElement and SVGContentCreatorFunction
+    // argument types is annoying.
+    nsCOMPtr<Element> xmlElement;
+    DebugOnly<nsresult> rv =
+        NS_NewXMLElement(getter_AddRefs(xmlElement), nodeInfo.forget());
+    MOZ_ASSERT(NS_SUCCEEDED(rv) && xmlElement);
+    newElement = xmlElement;
+  }
+
+  Element* newContent = newElement->AsElement();
+  aBuilder->HoldElement(newElement.forget());
+
+  if (MOZ_UNLIKELY(aName == nsGkAtoms::style)) {
+    if (auto* linkStyle = LinkStyle::FromNode(*newContent)) {
+      linkStyle->DisableUpdates();
+    }
+  }
+
+  if (!aAttributes) {
+    return newContent;
+  }
+
+  if (aAttributes->getDuplicateAttributeError()) {
+    newContent->SetParserHadDuplicateAttributeError();
+  }
+
+  int32_t len = aAttributes->getLength();
+  for (int32_t i = 0; i < len; i++) {
+    nsHtml5String val = aAttributes->getValueNoBoundsCheck(i);
+    nsAtom* klass = val.MaybeAsAtom();
+    if (klass) {
+      newContent->SetClassAttrFromParser(klass);
+    } else {
+      nsAtom* localName = aAttributes->getLocalNameNoBoundsCheck(i);
+      nsAtom* prefix = aAttributes->getPrefixNoBoundsCheck(i);
+      int32_t nsuri = aAttributes->getURINoBoundsCheck(i);
+
+      nsString value;  // Not Auto, because using it to hold nsStringBuffer*
+      val.ToString(value);
+      newContent->SetAttr(nsuri, localName, prefix, value, false);
+    }
+  }
+  return newContent;
+}
+
+nsIContent* nsHtml5TreeOperation::CreateMathMLElement(
+    nsAtom* aName, nsHtml5HtmlAttributes* aAttributes,
+    nsNodeInfoManager* aNodeInfoManager, nsHtml5DocumentBuilder* aBuilder) {
+  nsCOMPtr<Element> newElement;
+  if (MOZ_LIKELY(aNodeInfoManager->MathMLEnabled())) {
+    RefPtr<NodeInfo> nodeInfo = aNodeInfoManager->GetNodeInfo(
+        aName, nullptr, kNameSpaceID_MathML, nsINode::ELEMENT_NODE);
+    NS_ASSERTION(nodeInfo, "Got null nodeinfo.");
+
+    DebugOnly<nsresult> rv =
+        NS_NewMathMLElement(getter_AddRefs(newElement), nodeInfo.forget());
+    MOZ_ASSERT(NS_SUCCEEDED(rv) && newElement);
+  } else {
+    RefPtr<NodeInfo> nodeInfo = aNodeInfoManager->GetNodeInfo(
+        aName, nullptr, kNameSpaceID_disabled_MathML, nsINode::ELEMENT_NODE);
+    NS_ASSERTION(nodeInfo, "Got null nodeinfo.");
+
+    DebugOnly<nsresult> rv =
+        NS_NewXMLElement(getter_AddRefs(newElement), nodeInfo.forget());
+    MOZ_ASSERT(NS_SUCCEEDED(rv) && newElement);
+  }
+
+  Element* newContent = newElement;
+  aBuilder->HoldElement(newElement.forget());
+
+  if (!aAttributes) {
+    return newContent;
+  }
+
+  if (aAttributes->getDuplicateAttributeError()) {
+    newContent->SetParserHadDuplicateAttributeError();
+  }
+
+  int32_t len = aAttributes->getLength();
+  for (int32_t i = 0; i < len; i++) {
+    nsHtml5String val = aAttributes->getValueNoBoundsCheck(i);
+    nsAtom* klass = val.MaybeAsAtom();
+    if (klass) {
+      newContent->SetClassAttrFromParser(klass);
+    } else {
+      nsAtom* localName = aAttributes->getLocalNameNoBoundsCheck(i);
+      nsAtom* prefix = aAttributes->getPrefixNoBoundsCheck(i);
+      int32_t nsuri = aAttributes->getURINoBoundsCheck(i);
+
+      nsString value;  // Not Auto, because using it to hold nsStringBuffer*
+      val.ToString(value);
+      newContent->SetAttr(nsuri, localName, prefix, value, false);
+    }
+  }
+  return newContent;
+}
+
+void nsHtml5TreeOperation::SetFormElement(nsIContent* aNode,
+                                          nsIContent* aParent) {
+  RefPtr formElement = HTMLFormElement::FromNodeOrNull(aParent);
+  NS_ASSERTION(formElement,
+               "The form element doesn't implement HTMLFormElement.");
+  nsCOMPtr<nsIFormControl> formControl(do_QueryInterface(aNode));
+  if (formControl &&
+      formControl->ControlType() !=
+          FormControlType::FormAssociatedCustomElement &&
+      !aNode->AsElement()->HasAttr(nsGkAtoms::form)) {
+    formControl->SetForm(formElement);
+  } else if (auto* image = HTMLImageElement::FromNodeOrNull(aNode)) {
+    image->SetForm(formElement);
+  }
+}
+
+nsresult nsHtml5TreeOperation::FosterParentText(
+    nsIContent* aStackParent, char16_t* aBuffer, uint32_t aLength,
+    nsIContent* aTable, nsHtml5DocumentBuilder* aBuilder) {
+  MOZ_ASSERT(aBuilder);
+  MOZ_ASSERT(aBuilder->IsInDocUpdate());
+  nsresult rv = NS_OK;
+  nsIContent* foster = aTable->GetParent();
+
+  if (IsElementOrTemplateContent(foster)) {
+    nsHtml5OtherDocUpdate update(foster->OwnerDoc(), aBuilder->GetDocument());
+
+    nsIContent* previousSibling = aTable->GetPreviousSibling();
+    if (previousSibling && previousSibling->IsText()) {
+      return AppendTextToTextNode(aBuffer, aLength,
+                                  previousSibling->GetAsText(), aBuilder);
+    }
+
+    nsNodeInfoManager* nodeInfoManager =
+        aStackParent->OwnerDoc()->NodeInfoManager();
+    RefPtr<nsTextNode> text = new (nodeInfoManager) nsTextNode(nodeInfoManager);
+    NS_ASSERTION(text, "Infallible malloc failed?");
+    rv = text->SetText(aBuffer, aLength, false);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    ErrorResult error;
+    foster->InsertChildBefore(text, aTable, false, error);
+    if (error.Failed()) {
+      return error.StealNSResult();
+    }
+
+    MutationObservers::NotifyContentInserted(foster, text);
+    return rv;
+  }
+
+  return AppendText(aBuffer, aLength, aStackParent, aBuilder);
+}
+
+nsresult nsHtml5TreeOperation::AppendComment(nsIContent* aParent,
+                                             char16_t* aBuffer, int32_t aLength,
+                                             nsHtml5DocumentBuilder* aBuilder) {
+  nsNodeInfoManager* nodeInfoManager = aParent->OwnerDoc()->NodeInfoManager();
+  RefPtr<Comment> comment = new (nodeInfoManager) Comment(nodeInfoManager);
+  NS_ASSERTION(comment, "Infallible malloc failed?");
+  nsresult rv = comment->SetText(aBuffer, aLength, false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return Append(comment, aParent, aBuilder);
+}
+
+nsresult nsHtml5TreeOperation::AppendCommentToDocument(
+    char16_t* aBuffer, int32_t aLength, nsHtml5DocumentBuilder* aBuilder) {
+  RefPtr<Comment> comment = new (aBuilder->GetNodeInfoManager())
+      Comment(aBuilder->GetNodeInfoManager());
+  NS_ASSERTION(comment, "Infallible malloc failed?");
+  nsresult rv = comment->SetText(aBuffer, aLength, false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return AppendToDocument(comment, aBuilder);
+}
+
+nsresult nsHtml5TreeOperation::AppendDoctypeToDocument(
+    nsAtom* aName, const nsAString& aPublicId, const nsAString& aSystemId,
+    nsHtml5DocumentBuilder* aBuilder) {
+  // Adapted from nsXMLContentSink
+  // Create a new doctype node
+  RefPtr<DocumentType> docType =
+      NS_NewDOMDocumentType(aBuilder->GetNodeInfoManager(), aName, aPublicId,
+                            aSystemId, VoidString());
+  return AppendToDocument(docType, aBuilder);
+}
+
+nsIContent* nsHtml5TreeOperation::GetDocumentFragmentForTemplate(
+    nsIContent* aNode) {
+  auto* tempElem = static_cast<HTMLTemplateElement*>(aNode);
+  return tempElem->Content();
+}
+
+void nsHtml5TreeOperation::SetDocumentFragmentForTemplate(
+    nsIContent* aNode, nsIContent* aDocumentFragment) {
+  auto* tempElem = static_cast<HTMLTemplateElement*>(aNode);
+  tempElem->SetContent(static_cast<DocumentFragment*>(aDocumentFragment));
+}
+
+nsIContent* nsHtml5TreeOperation::GetFosterParent(nsIContent* aTable,
+                                                  nsIContent* aStackParent) {
+  nsIContent* tableParent = aTable->GetParent();
+  return IsElementOrTemplateContent(tableParent) ? tableParent : aStackParent;
+}
+
+void nsHtml5TreeOperation::PreventScriptExecution(nsIContent* aNode) {
+  nsCOMPtr<nsIScriptElement> sele = do_QueryInterface(aNode);
+  if (sele) {
+    sele->PreventExecution();
+  } else {
+    MOZ_ASSERT(nsNameSpaceManager::GetInstance()->mSVGDisabled,
+               "Node didn't QI to script, but SVG wasn't disabled.");
+  }
+}
+
+void nsHtml5TreeOperation::DoneAddingChildren(nsIContent* aNode) {
+  aNode->DoneAddingChildren(aNode->HasParserNotified());
+}
+
+void nsHtml5TreeOperation::DoneCreatingElement(nsIContent* aNode) {
+  aNode->DoneCreatingElement();
+}
+
+void nsHtml5TreeOperation::SvgLoad(nsIContent* aNode) {
+  nsCOMPtr<nsIRunnable> event = new nsHtml5SVGLoadDispatcher(aNode);
+  if (NS_FAILED(aNode->OwnerDoc()->Dispatch(event.forget()))) {
+    NS_WARNING("failed to dispatch svg load dispatcher");
+  }
+}
+
+void nsHtml5TreeOperation::MarkMalformedIfScript(nsIContent* aNode) {
+  nsCOMPtr<nsIScriptElement> sele = do_QueryInterface(aNode);
+  if (sele) {
+    // Make sure to serialize this script correctly, for nice round tripping.
+    sele->SetIsMalformed();
+  }
+}
+
+nsresult nsHtml5TreeOperation::Perform(nsHtml5TreeOpExecutor* aBuilder,
+                                       nsIContent** aScriptElement,
+                                       bool* aInterrupted, bool* aStreamEnded) {
+  struct TreeOperationMatcher {
+    TreeOperationMatcher(nsHtml5TreeOpExecutor* aBuilder,
+                         nsIContent** aScriptElement, bool* aInterrupted,
+                         bool* aStreamEnded)
+        : mBuilder(aBuilder),
+          mScriptElement(aScriptElement),
+          mInterrupted(aInterrupted),
+          mStreamEnded(aStreamEnded) {}
+
+    nsHtml5TreeOpExecutor* mBuilder;
+    nsIContent** mScriptElement;
+    bool* mInterrupted;
+    bool* mStreamEnded;
+
+    nsresult operator()(const opAppend& aOperation) {
+      return Append(*(aOperation.mChild), *(aOperation.mParent),
+                    aOperation.mFromNetwork, mBuilder);
+    }
+
+    nsresult operator()(const opDetach& aOperation) {
+      Detach(*(aOperation.mElement), mBuilder);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opAppendChildrenToNewParent& aOperation) {
+      nsCOMPtr<nsIContent> node = *(aOperation.mOldParent);
+      nsIContent* parent = *(aOperation.mNewParent);
+      return AppendChildrenToNewParent(node, parent, mBuilder);
+    }
+
+    nsresult operator()(const opFosterParent& aOperation) {
+      nsIContent* node = *(aOperation.mChild);
+      nsIContent* parent = *(aOperation.mStackParent);
+      nsIContent* table = *(aOperation.mTable);
+      return FosterParent(node, parent, table, mBuilder);
+    }
+
+    nsresult operator()(const opAppendToDocument& aOperation) {
+      nsresult rv = AppendToDocument(*(aOperation.mContent), mBuilder);
+      mBuilder->PauseDocUpdate(mInterrupted);
+      return rv;
+    }
+
+    nsresult operator()(const opAddAttributes& aOperation) {
+      nsIContent* node = *(aOperation.mElement);
+      nsHtml5HtmlAttributes* attributes = aOperation.mAttributes;
+      return AddAttributes(node, attributes, mBuilder);
+    }
+
+    nsresult operator()(const nsHtml5DocumentMode& aMode) {
+      mBuilder->SetDocumentMode(aMode);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opCreateHTMLElement& aOperation) {
+      nsIContent** target = aOperation.mContent;
+      HTMLContentCreatorFunction creator = aOperation.mCreator;
+      nsAtom* name = aOperation.mName;
+      nsHtml5HtmlAttributes* attributes = aOperation.mAttributes;
+      nsIContent* intendedParent =
+          aOperation.mIntendedParent ? *(aOperation.mIntendedParent) : nullptr;
+
+      // intendedParent == nullptr is a special case where the
+      // intended parent is the document.
+      nsNodeInfoManager* nodeInfoManager =
+          intendedParent ? intendedParent->OwnerDoc()->NodeInfoManager()
+                         : mBuilder->GetNodeInfoManager();
+
+      *target = CreateHTMLElement(name, attributes, aOperation.mFromNetwork,
+                                  nodeInfoManager, mBuilder, creator);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opCreateSVGElement& aOperation) {
+      nsIContent** target = aOperation.mContent;
+      SVGContentCreatorFunction creator = aOperation.mCreator;
+      nsAtom* name = aOperation.mName;
+      nsHtml5HtmlAttributes* attributes = aOperation.mAttributes;
+      nsIContent* intendedParent =
+          aOperation.mIntendedParent ? *(aOperation.mIntendedParent) : nullptr;
+
+      // intendedParent == nullptr is a special case where the
+      // intended parent is the document.
+      nsNodeInfoManager* nodeInfoManager =
+          intendedParent ? intendedParent->OwnerDoc()->NodeInfoManager()
+                         : mBuilder->GetNodeInfoManager();
+
+      *target = CreateSVGElement(name, attributes, aOperation.mFromNetwork,
+                                 nodeInfoManager, mBuilder, creator);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opCreateMathMLElement& aOperation) {
+      nsIContent** target = aOperation.mContent;
+      nsAtom* name = aOperation.mName;
+      nsHtml5HtmlAttributes* attributes = aOperation.mAttributes;
+      nsIContent* intendedParent =
+          aOperation.mIntendedParent ? *(aOperation.mIntendedParent) : nullptr;
+
+      // intendedParent == nullptr is a special case where the
+      // intended parent is the document.
+      nsNodeInfoManager* nodeInfoManager =
+          intendedParent ? intendedParent->OwnerDoc()->NodeInfoManager()
+                         : mBuilder->GetNodeInfoManager();
+
+      *target =
+          CreateMathMLElement(name, attributes, nodeInfoManager, mBuilder);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opSetFormElement& aOperation) {
+      SetFormElement(*(aOperation.mContent), *(aOperation.mFormElement));
+      return NS_OK;
+    }
+
+    nsresult operator()(const opAppendText& aOperation) {
+      nsIContent* parent = *aOperation.mParent;
+      char16_t* buffer = aOperation.mBuffer;
+      uint32_t length = aOperation.mLength;
+      return AppendText(buffer, length, parent, mBuilder);
+    }
+
+    nsresult operator()(const opFosterParentText& aOperation) {
+      nsIContent* stackParent = *aOperation.mStackParent;
+      char16_t* buffer = aOperation.mBuffer;
+      uint32_t length = aOperation.mLength;
+      nsIContent* table = *aOperation.mTable;
+      return FosterParentText(stackParent, buffer, length, table, mBuilder);
+    }
+
+    nsresult operator()(const opAppendComment& aOperation) {
+      nsIContent* parent = *aOperation.mParent;
+      char16_t* buffer = aOperation.mBuffer;
+      uint32_t length = aOperation.mLength;
+      return AppendComment(parent, buffer, length, mBuilder);
+    }
+
+    nsresult operator()(const opAppendCommentToDocument& aOperation) {
+      char16_t* buffer = aOperation.mBuffer;
+      int32_t length = aOperation.mLength;
+      return AppendCommentToDocument(buffer, length, mBuilder);
+    }
+
+    nsresult operator()(const opAppendDoctypeToDocument& aOperation) {
+      nsAtom* name = aOperation.mName;
+      nsHtml5TreeOperationStringPair* pair = aOperation.mStringPair;
+      nsString publicId;
+      nsString systemId;
+      pair->Get(publicId, systemId);
+      return AppendDoctypeToDocument(name, publicId, systemId, mBuilder);
+    }
+
+    nsresult operator()(const opGetDocumentFragmentForTemplate& aOperation) {
+      nsIContent* node = *(aOperation.mTemplate);
+      *(aOperation.mFragHandle) = GetDocumentFragmentForTemplate(node);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opSetDocumentFragmentForTemplate& aOperation) {
+      SetDocumentFragmentForTemplate(*aOperation.mTemplate,
+                                     *aOperation.mFragment);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opGetShadowRootFromHost& aOperation) {
+      nsIContent* root = nsContentUtils::AttachDeclarativeShadowRoot(
+          *aOperation.mHost, aOperation.mShadowRootMode,
+          aOperation.mShadowRootDelegatesFocus);
+      if (root) {
+        *aOperation.mFragHandle = root;
+        return NS_OK;
+      }
+
+      // We failed to attach a new shadow root, so instead attach a template
+      // element and return its content.
+      nsHtml5TreeOperation::Append(*aOperation.mTemplateNode, *aOperation.mHost,
+                                   mBuilder);
+      *aOperation.mFragHandle =
+          static_cast<HTMLTemplateElement*>(*aOperation.mTemplateNode)
+              ->Content();
+      nsContentUtils::LogSimpleConsoleError(
+          u"Failed to attach Declarative Shadow DOM."_ns, "DOM"_ns,
+          mBuilder->GetDocument()->IsInPrivateBrowsing(),
+          mBuilder->GetDocument()->IsInChromeDocShell());
+      return NS_OK;
+    }
+
+    nsresult operator()(const opGetFosterParent& aOperation) {
+      nsIContent* table = *(aOperation.mTable);
+      nsIContent* stackParent = *(aOperation.mStackParent);
+      nsIContent* fosterParent = GetFosterParent(table, stackParent);
+      *aOperation.mParentHandle = fosterParent;
+      return NS_OK;
+    }
+
+    nsresult operator()(const opMarkAsBroken& aOperation) {
+      return aOperation.mResult;
+    }
+
+    nsresult operator()(
+        const opRunScriptThatMayDocumentWriteOrBlock& aOperation) {
+      nsIContent* node = *(aOperation.mElement);
+      nsAHtml5TreeBuilderState* snapshot = aOperation.mBuilderState;
+      if (snapshot) {
+        mBuilder->InitializeDocWriteParserState(snapshot,
+                                                aOperation.mLineNumber);
+      }
+      *mScriptElement = node;
+      return NS_OK;
+    }
+
+    nsresult operator()(
+        const opRunScriptThatCannotDocumentWriteOrBlock& aOperation) {
+      mBuilder->RunScript(*(aOperation.mElement), false);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opPreventScriptExecution& aOperation) {
+      PreventScriptExecution(*(aOperation.mElement));
+      return NS_OK;
+    }
+
+    nsresult operator()(const opDoneAddingChildren& aOperation) {
+      nsIContent* node = *(aOperation.mElement);
+      node->DoneAddingChildren(node->HasParserNotified());
+      return NS_OK;
+    }
+
+    nsresult operator()(const opDoneCreatingElement& aOperation) {
+      DoneCreatingElement(*(aOperation.mElement));
+      return NS_OK;
+    }
+
+    nsresult operator()(const opUpdateCharsetSource& aOperation) {
+      mBuilder->UpdateCharsetSource(aOperation.mCharsetSource);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opCharsetSwitchTo& aOperation) {
+      auto encoding = WrapNotNull(aOperation.mEncoding);
+      mBuilder->NeedsCharsetSwitchTo(encoding, aOperation.mCharsetSource,
+                                     (uint32_t)aOperation.mLineNumber);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opUpdateStyleSheet& aOperation) {
+      mBuilder->UpdateStyleSheet(*(aOperation.mElement));
+      return NS_OK;
+    }
+
+    nsresult operator()(const opProcessOfflineManifest& aOperation) {
+      // TODO: remove this
+      return NS_OK;
+    }
+
+    nsresult operator()(const opMarkMalformedIfScript& aOperation) {
+      MarkMalformedIfScript(*(aOperation.mElement));
+      return NS_OK;
+    }
+
+    nsresult operator()(const opStreamEnded& aOperation) {
+      *mStreamEnded = true;
+      return NS_OK;
+    }
+
+    nsresult operator()(const opSetStyleLineNumber& aOperation) {
+      nsIContent* node = *(aOperation.mContent);
+      if (auto* linkStyle = LinkStyle::FromNode(*node)) {
+        linkStyle->SetLineNumber(aOperation.mLineNumber);
+      } else {
+        MOZ_ASSERT(nsNameSpaceManager::GetInstance()->mSVGDisabled,
+                   "Node didn't QI to style, but SVG wasn't disabled.");
+      }
+      return NS_OK;
+    }
+
+    nsresult operator()(
+        const opSetScriptLineAndColumnNumberAndFreeze& aOperation) {
+      nsIContent* node = *(aOperation.mContent);
+      nsCOMPtr<nsIScriptElement> sele = do_QueryInterface(node);
+      if (sele) {
+        sele->SetScriptLineNumber(aOperation.mLineNumber);
+        sele->SetScriptColumnNumber(
+            JS::ColumnNumberOneOrigin(aOperation.mColumnNumber));
+        sele->FreezeExecutionAttrs(node->OwnerDoc());
+      } else {
+        MOZ_ASSERT(nsNameSpaceManager::GetInstance()->mSVGDisabled,
+                   "Node didn't QI to script, but SVG wasn't disabled.");
+      }
+      return NS_OK;
+    }
+
+    nsresult operator()(const opSvgLoad& aOperation) {
+      SvgLoad(*(aOperation.mElement));
+      return NS_OK;
+    }
+
+    nsresult operator()(const opMaybeComplainAboutCharset& aOperation) {
+      char* msgId = aOperation.mMsgId;
+      bool error = aOperation.mError;
+      int32_t lineNumber = aOperation.mLineNumber;
+      mBuilder->MaybeComplainAboutCharset(msgId, error, (uint32_t)lineNumber);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opMaybeComplainAboutDeepTree& aOperation) {
+      mBuilder->MaybeComplainAboutDeepTree((uint32_t)aOperation.mLineNumber);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opAddClass& aOperation) {
+      Element* element = (*(aOperation.mElement))->AsElement();
+      char16_t* str = aOperation.mClass;
+      nsDependentString depStr(str);
+      // See viewsource.css for the possible classes
+      nsAutoString klass;
+      element->GetAttr(nsGkAtoms::_class, klass);
+      if (!klass.IsEmpty()) {
+        klass.Append(' ');
+        klass.Append(depStr);
+        element->SetAttr(kNameSpaceID_None, nsGkAtoms::_class, klass, true);
+      } else {
+        element->SetAttr(kNameSpaceID_None, nsGkAtoms::_class, depStr, true);
+      }
+      return NS_OK;
+    }
+
+    nsresult operator()(const opAddViewSourceHref& aOperation) {
+      Element* element = (*aOperation.mElement)->AsElement();
+      char16_t* buffer = aOperation.mBuffer;
+      int32_t length = aOperation.mLength;
+      nsDependentString relative(buffer, length);
+
+      Document* doc = mBuilder->GetDocument();
+
+      auto encoding = doc->GetDocumentCharacterSet();
+      nsCOMPtr<nsIURI> uri;
+      nsresult rv = NS_NewURI(getter_AddRefs(uri), relative, encoding,
+                              mBuilder->GetViewSourceBaseURI());
+      NS_ENSURE_SUCCESS(rv, NS_OK);
+
+      // Reuse the fix for bug 467852
+      // URLs that execute script (e.g. "javascript:" URLs) should just be
+      // ignored.  There's nothing reasonable we can do with them, and allowing
+      // them to execute in the context of the view-source window presents a
+      // security risk.  Just return the empty string in this case.
+      bool openingExecutesScript = false;
+      rv = NS_URIChainHasFlags(uri,
+                               nsIProtocolHandler::URI_OPENING_EXECUTES_SCRIPT,
+                               &openingExecutesScript);
+      if (NS_FAILED(rv) || openingExecutesScript) {
+        return NS_OK;
+      }
+
+      nsAutoCString viewSourceUrl;
+
+      // URLs that return data (e.g. "http:" URLs) should be prefixed with
+      // "view-source:".  URLs that don't return data should just be returned
+      // undecorated.
+      if (!nsContentUtils::IsExternalProtocol(uri)) {
+        viewSourceUrl.AssignLiteral("view-source:");
+      }
+
+      nsAutoCString spec;
+      rv = uri->GetSpec(spec);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      viewSourceUrl.Append(spec);
+
+      nsAutoString utf16;
+      CopyUTF8toUTF16(viewSourceUrl, utf16);
+
+      element->SetAttr(kNameSpaceID_None, nsGkAtoms::href, utf16, true);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opAddViewSourceBase& aOperation) {
+      nsDependentString baseUrl(aOperation.mBuffer, aOperation.mLength);
+      mBuilder->AddBase(baseUrl);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opAddErrorType& aOperation) {
+      Element* element = (*(aOperation.mElement))->AsElement();
+      char* msgId = aOperation.mMsgId;
+      nsAtom* atom = aOperation.mName;
+      nsAtom* otherAtom = aOperation.mOther;
+      // See viewsource.css for the possible classes in addition to "error".
+      nsAutoString klass;
+      element->GetAttr(nsGkAtoms::_class, klass);
+      if (!klass.IsEmpty()) {
+        klass.AppendLiteral(" error");
+        element->SetAttr(kNameSpaceID_None, nsGkAtoms::_class, klass, true);
+      } else {
+        element->SetAttr(kNameSpaceID_None, nsGkAtoms::_class, u"error"_ns,
+                         true);
+      }
+
+      nsresult rv;
+      nsAutoString message;
+      if (otherAtom) {
+        rv = nsContentUtils::FormatLocalizedString(
+            message, nsContentUtils::eHTMLPARSER_PROPERTIES, msgId,
+            nsDependentAtomString(atom), nsDependentAtomString(otherAtom));
+        NS_ENSURE_SUCCESS(rv, NS_OK);
+      } else if (atom) {
+        rv = nsContentUtils::FormatLocalizedString(
+            message, nsContentUtils::eHTMLPARSER_PROPERTIES, msgId,
+            nsDependentAtomString(atom));
+        NS_ENSURE_SUCCESS(rv, NS_OK);
+      } else {
+        rv = nsContentUtils::GetLocalizedString(
+            nsContentUtils::eHTMLPARSER_PROPERTIES, msgId, message);
+        NS_ENSURE_SUCCESS(rv, NS_OK);
+      }
+
+      nsAutoString title;
+      element->GetAttr(nsGkAtoms::title, title);
+      if (!title.IsEmpty()) {
+        title.Append('\n');
+        title.Append(message);
+        element->SetAttr(kNameSpaceID_None, nsGkAtoms::title, title, true);
+      } else {
+        element->SetAttr(kNameSpaceID_None, nsGkAtoms::title, message, true);
+      }
+      return rv;
+    }
+
+    nsresult operator()(const opAddLineNumberId& aOperation) {
+      Element* element = (*(aOperation.mElement))->AsElement();
+      int32_t lineNumber = aOperation.mLineNumber;
+      nsAutoString val(u"line"_ns);
+      val.AppendInt(lineNumber);
+      element->SetAttr(kNameSpaceID_None, nsGkAtoms::id, val, true);
+      return NS_OK;
+    }
+
+    nsresult operator()(const opStartLayout& aOperation) {
+      mBuilder->StartLayout(
+          mInterrupted);  // this causes a notification flush anyway
+      return NS_OK;
+    }
+
+    nsresult operator()(const opEnableEncodingMenu& aOperation) {
+      Document* doc = mBuilder->GetDocument();
+      doc->EnableEncodingMenu();
+      return NS_OK;
+    }
+
+    nsresult operator()(const uninitialized& aOperation) {
+      MOZ_CRASH("uninitialized");
+      return NS_OK;
+    }
+  };
+
+  return mOperation.match(TreeOperationMatcher(aBuilder, aScriptElement,
+                                               aInterrupted, aStreamEnded));
+}