Invalidate the previous caret location when editing text nodes.

third_party/WebKit/Source/core/dom/Document.h

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index e102c0b0955a2c01c4bc8865f61e7e256c8929be..dd523dfa00ab5e83a64f738a0c6a963b9379ad2d 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -77,6 +77,7 @@ class CancellableTaskFactory;
 class CanvasFontCache;
 class CanvasRenderingContext2D;
 class CanvasRenderingContext2DOrWebGLRenderingContext;
+class CharacterData;
 class ChromeClient;
 class CompositorPendingAnimations;
 class Comment;
@@ -640,6 +641,8 @@ public:
     void nodeChildrenWillBeRemoved(ContainerNode&);
     // nodeWillBeRemoved is only safe when removing one node at a time.
     void nodeWillBeRemoved(Node&);
+    // Called just before a destructive update to some CharacterData.
+    void dataWillChange(const CharacterData&);
     bool canAcceptChild(const Node& newChild, const Node* oldChild, ExceptionState&) const;
 
     void didInsertText(Node*, unsigned offset, unsigned length);