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

Source/core/editing/FrameSelection.cpp

 /*
  * Copyright (C) 2004, 2008, 2009, 2010 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1204 matching lines @@
 RenderBlock* FrameSelection::caretRenderer() const
 {
     return CaretBase::caretRenderer(m_selection.start().deprecatedNode());
 }
 
 static bool isNonOrphanedCaret(const VisibleSelection& selection)
 {
     return selection.isCaret() && !selection.start().isOrphan() && !selection.end().isOrphan();
 }
 
+static bool isTextFormControl(const VisibleSelection& selection)
+{
+    return !!enclosingTextFormControl(selection.start());

[yosin_UTC9, 2014/07/29 07:00:20]

nit: I don't think we need to use |!!| for casting pointer to |bool|.

[yoichio, 2014/07/29 08:05:17]

Done.

+}
+
 LayoutRect FrameSelection::localCaretRect()
 {
     if (shouldUpdateCaretRect()) {
-        if (!isNonOrphanedCaret(m_selection))
+        if (!isNonOrphanedCaret(m_selection)) {
             clearCaretRect();
-        else if (updateCaretRect(m_frame->document(), VisiblePosition(m_selection.start(), m_selection.affinity())))
-            m_absCaretBoundsDirty = true;
+        } else {
+            if (isTextFormControl(m_selection))

[yosin_UTC9, 2014/07/29 07:00:20]

nit: We can combine |else| and |if|.

[yoichio, 2014/07/29 08:05:17]

Done.

+                m_absCaretBoundsDirty |= updateCaretRect(m_frame->document(), PositionWithAffinity(m_selection.start().isCandidate() ? m_selection.start() : Position(), m_selection.affinity()));

[yosin_UTC9, 2014/07/29 07:00:20]

Q: Why do we need to check |start()| is editable position?

[yoichio, 2014/07/29 08:05:17]

updateCaretRect suppose that an argument Visible position is Null if start is
not on editable position.

+            else
+                m_absCaretBoundsDirty |= updateCaretRect(m_frame->document(), VisiblePosition(m_selection.start(), m_selection.affinity()));
+        }
     }
 
     return localCaretRectWithoutUpdate();
 }
 
 IntRect FrameSelection::absoluteCaretBounds()
 {
     recomputeCaretRect();
     return m_absCaretBounds;
 }
@@ skipping 676 matching lines @@
     sel.showTreeForThis();
 }
 
 void showTree(const blink::FrameSelection* sel)
 {
     if (sel)
         sel->showTreeForThis();
 }
 
 #endif