Reduce compositing update in Silk's toggle_drawer by 20%

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 512b4828f3961fc5612afcd8233161d04854eaad..499fd8e9efb6e830c679dd5cd2be707411337fee 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -3504,6 +3504,7 @@ CompositedLayerMappingPtr RenderLayer::ensureCompositedLayerMapping()
 {
     if (!m_compositedLayerMapping) {
         m_compositedLayerMapping = adoptPtr(new CompositedLayerMapping(this));
+        m_compositedLayerMapping->setNeedsGeometryUpdate();
 
         updateOrRemoveFilterEffectRenderer();
 
@@ -3870,6 +3871,9 @@ void RenderLayer::styleChanged(StyleDifference diff, const RenderStyle* oldStyle
     // https://code.google.com/p/chromium/issues/detail?id=343756
     DisableCompositingQueryAsserts disabler;
 
+    if (hasCompositedLayerMapping())
+        compositedLayerMapping()->setNeedsGeometryUpdate();
+
     const RenderStyle* newStyle = renderer()->style();
 
     compositor()->updateLayerCompositingState(this, RenderLayerCompositor::UseChickenEggHacks);