Properly repaint RenderLayer's descendants when it moves

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 241 matching lines @@
     TRACE_EVENT0("blink_rendering", "RenderLayer::updateLayerPositionsAfterLayout");
 
     // FIXME: Remove incremental compositing updates after fixing the chicken/egg issues
     // https://code.google.com/p/chromium/issues/detail?id=343756
     DisableCompositingQueryAsserts disabler;
     updateLayerPositionRecursive(flags);
 }
 
 void RenderLayer::updateLayerPositionRecursive(UpdateLayerPositionsFlags flags)
 {
-    updateLayerPosition();
+    if (flags & ForceMayNeedPaintInvalidation)
+        m_renderer->setMayNeedPaintInvalidation(true);
+
+    if (updateLayerPosition())
+        flags |= ForceMayNeedPaintInvalidation;
 
     // Clear our cached clip rect information.
     m_clipper.clearClipRects();
 
     if (hasOverflowControls()) {
         // FIXME: We should figure out the right time to position the overflow controls.
         // This call appears to be necessary to pass some layout test that use EventSender,
         // presumably because the normal time to position the controls is during paint. We
         // probably shouldn't position the overflow controls during paint either...
         scrollableArea()->positionOverflowControls(IntSize());
@@ skipping 3508 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif