Don't schedule an animation during compositing dirty-bit setting unless needed.

Source/web/PageWidgetDelegate.cpp

Index: Source/web/PageWidgetDelegate.cpp
diff --git a/Source/web/PageWidgetDelegate.cpp b/Source/web/PageWidgetDelegate.cpp
index 0c7ab2aa17c25b0a0554f833e9f302d36b74568d..59a4df03517e3c75f4e5310c88fbe003d37ee431 100644
--- a/Source/web/PageWidgetDelegate.cpp
+++ b/Source/web/PageWidgetDelegate.cpp
@@ -68,20 +68,9 @@ void PageWidgetDelegate::animate(Page* page, double monotonicFrameBeginTime)
 
 void PageWidgetDelegate::layout(Page* page)
 {
-    RefPtr<FrameView> view = mainFrameView(page);
-    if (!view)
+    if (!page || !page->mainFrame())
         return;
-    // In order for our child HWNDs (NativeWindowWidgets) to update properly,
-    // they need to be told that we are updating the screen. The problem is that
-    // the native widgets need to recalculate their clip region and not overlap
-    // any of our non-native widgets. To force the resizing, call
-    // setFrameRect(). This will be a quick operation for most frames, but the
-    // NativeWindowWidgets will update a proper clipping region.
-    view->setFrameRect(view->frameRect());
-
-    // setFrameRect may have the side-effect of causing existing page layout to
-    // be invalidated, so layout needs to be called last.
-    view->updateLayoutAndStyleForPainting();
+    page->animator().updateLayoutAndStyleForPainting();
 }
 
 void PageWidgetDelegate::paint(Page* page, PageOverlayList* overlays, WebCanvas* canvas, const WebRect& rect, CanvasBackground background)