Let FrameSelection::localCaretRect on a text input field avoid synchronous layout.

Source/core/editing/VisiblePosition.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Portions Copyright (c) 2011 Motorola Mobility, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 631 matching lines @@
     Text* textNode = pos.containerText();
     unsigned length = textNode->length();
     if (offset >= length)
         return 0;
 
     return textNode->data().characterStartingAt(offset);
 }
 
 LayoutRect VisiblePosition::localCaretRect(RenderObject*& renderer) const
 {
-    if (m_deepPosition.isNull()) {
-        renderer = 0;
-        return IntRect();
-    }
-    Node* node = m_deepPosition.anchorNode();
-
-    renderer = node->renderer();
-    if (!renderer)
-        return LayoutRect();
-
-    InlineBox* inlineBox;
-    int caretOffset;
-    getInlineBoxAndOffset(inlineBox, caretOffset);
-
-    if (inlineBox)
-        renderer = &inlineBox->renderer();
-
-    return renderer->localCaretRect(inlineBox, caretOffset);
+    PositionWithAffinity positionWithAffinity(m_deepPosition, m_affinity);
+    return localCaretRectOfPosition(positionWithAffinity, renderer);
 }
 
 IntRect VisiblePosition::absoluteCaretBounds() const
 {
     RenderObject* renderer;
     LayoutRect localRect = localCaretRect(renderer);
     if (localRect.isEmpty() || !renderer)
         return IntRect();
 
     return renderer->localToAbsoluteQuad(FloatRect(localRect)).enclosingBoundingBox();
@@ skipping 124 matching lines @@
     if (vpos)
         vpos->showTreeForThis();
 }
 
 void showTree(const blink::VisiblePosition& vpos)
 {
     vpos.showTreeForThis();
 }
 
 #endif