FrameSelection::updateApperance for caret should not cause layout.

Source/core/editing/Caret.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 52 matching lines @@
 {
     if (Node* node = m_position.deepEquivalent().deprecatedNode())
         invalidateCaretRect(node);
     m_position = position;
     setCaretRectNeedsUpdate();
     Document* document = 0;
     if (Node* node = m_position.deepEquivalent().deprecatedNode()) {
         invalidateCaretRect(node);
         document = &node->document();
     }
-    if (m_position.isNull() || m_position.isOrphan())
+    if (m_position.isNull() || m_position.isOrphan()) {
         clearCaretRect();
-    else
+    } else {
+        document->updateRenderTreeIfNeeded();
         updateCaretRect(document, m_position);
+    }
 }
 
 static bool removingNodeRemovesPosition(Node& node, const Position& position)
 {
     if (!position.anchorNode())
         return false;
 
     if (position.anchorNode() == node)
         return true;
 
@@ skipping 40 matching lines @@
     if (!renderer)
         return 0;
 
     // if caretNode is a block and caret is inside it then caret should be painted by that block
     bool paintedByBlock = renderer->isRenderBlock() && caretRendersInsideNode(node);
     return paintedByBlock ? toRenderBlock(renderer) : renderer->containingBlock();
 }
 
 bool CaretBase::updateCaretRect(Document* document, const PositionWithAffinity& caretPosition)
 {
-    document->updateRenderTreeIfNeeded();
     m_caretLocalRect = LayoutRect();
 
     m_caretRectNeedsUpdate = false;
 
     if (caretPosition.position().isNull())
         return false;
 
     ASSERT(caretPosition.position().deprecatedNode()->renderer());
 
     // First compute a rect local to the renderer at the selection start.
@@ skipping 119 matching lines @@
     context->fillRect(caret, caretColor);
 }
 
 void DragCaretController::paintDragCaret(LocalFrame* frame, GraphicsContext* p, const LayoutPoint& paintOffset, const LayoutRect& clipRect) const
 {
     if (m_position.deepEquivalent().deprecatedNode()->document().frame() == frame)
         paintCaret(m_position.deepEquivalent().deprecatedNode(), p, paintOffset, clipRect);
 }
 
 }