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diff --git a/dom/base/nsDOMCaretPosition.h b/dom/base/nsDOMCaretPosition.h
new file mode 100644
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+++ b/dom/base/nsDOMCaretPosition.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsDOMCaretPosition_h
+#define nsDOMCaretPosition_h
+
+#include "nsCycleCollectionParticipant.h"
+#include "nsCOMPtr.h"
+#include "nsINode.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla::dom {
+class DOMRect;
+}  // namespace mozilla::dom
+
+/**
+ * Implementation of a DOM Caret Position, which is a node and offset within
+ * that node, in the DOM tree.
+ *
+ * http://www.w3.org/TR/cssom-view/#dom-documentview-caretrangefrompoint
+ *
+ * @see Document::caretPositionFromPoint(float x, float y)
+ */
+class nsDOMCaretPosition : public nsISupports, public nsWrapperCache {
+  using DOMRect = mozilla::dom::DOMRect;
+
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(nsDOMCaretPosition)
+
+  nsDOMCaretPosition(nsINode* aNode, uint32_t aOffset);
+
+  /**
+   * Retrieve the offset (character position within the DOM node) of the
+   * CaretPosition.
+   *
+   * @returns The offset within the DOM node.
+   */
+  uint32_t Offset() const { return mOffset; }
+
+  /**
+   * Retrieve the DOM node with which this CaretPosition was established.
+   * Normally, this will be created from a point, so it will be the DOM
+   * node that lies at the point specified.
+   *
+   * @returns The DOM node of the CaretPosition.
+   *
+   * @see Document::caretPositionFromPoint(float x, float y)
+   */
+  nsINode* GetOffsetNode() const;
+
+  /**
+   * Retrieve the bounding rectangle of this CaretPosition object.
+   *
+   * @returns An nsClientRect representing the bounding rectangle of this
+   *          CaretPosition, if one can be successfully determined, otherwise
+   *          nullptr.
+   */
+  already_AddRefed<DOMRect> GetClientRect() const;
+
+  /**
+   * Set the anonymous content node that is the actual parent of this
+   * CaretPosition object. In situations where the DOM node for a CaretPosition
+   * actually lies within an anonymous content node (e.g. a textarea), the
+   * actual parent is not set as the offset node. This is used to get the
+   * correct bounding box of a CaretPosition object that lies within a textarea
+   * or input element.
+   *
+   * @param aNode A pointer to an nsINode object that is the actual element
+   *        within which this CaretPosition lies, but is an anonymous content
+   *        node.
+   */
+  void SetAnonymousContentNode(nsINode* aNode) {
+    mAnonymousContentNode = aNode;
+  }
+
+  nsISupports* GetParentObject() const { return GetOffsetNode(); }
+
+  JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) final;
+
+ protected:
+  virtual ~nsDOMCaretPosition();
+
+  uint32_t mOffset;
+  nsCOMPtr<nsINode> mOffsetNode;
+  nsCOMPtr<nsINode> mAnonymousContentNode;
+};
+#endif