Bug 620512. Part 1: Only fire MozPaintWait and change window visibility in BuildDisplayList if we're painting. r=bsmedberg, a=b:b9

layout/base/nsDisplayList.h

@@ -151,10 +151,14 @@ public:
    */
   PRBool IsForEventDelivery() { return mMode == EVENT_DELIVERY; }
   /**
-   * @return PR_TRUE if the display list is being build to compute geometry
+   * @return PR_TRUE if the display list is being built to compute geometry
    * for plugins.
    */
   PRBool IsForPluginGeometry() { return mMode == PLUGIN_GEOMETRY; }
+  /**
+   * @return PR_TRUE if the display list is being built for painting.
+   */
+  PRBool IsForPainting() { return mMode == PAINTING; }
   /**
    * @return PR_TRUE if "painting is suppressed" during page load and we
    * should paint only the background of the document.

layout/generic/nsObjectFrame.cpp

@@ -1469,7 +1469,7 @@ nsObjectFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
   nsDisplayList replacedContent;
 
-  if (mInstanceOwner && mInstanceOwner->UseLayers()) {
+  if (aBuilder->IsForPainting() && mInstanceOwner && mInstanceOwner->UseLayers()) {
     NPWindow* window = nsnull;
     mInstanceOwner->GetWindow(window);
     PRBool isVisible = window && window->width > 0 && window->height > 0;