diff --git a/dom/plugins/base/nsPluginInstanceOwner.cpp b/dom/plugins/base/nsPluginInstanceOwner.cpp
index fbe870b4951..1fa422d34d0 100644
--- a/dom/plugins/base/nsPluginInstanceOwner.cpp
+++ b/dom/plugins/base/nsPluginInstanceOwner.cpp
@@ -646,7 +646,6 @@ NS_IMETHODIMP nsPluginInstanceOwner::InvalidateRect(NPRect *invalidRect)
   // date and update our ImageContainer with the new surface.
   nsRefPtr<ImageContainer> container;
   mInstance->GetImageContainer(getter_AddRefs(container));
-  gfxIntSize oldSize(0, 0);
 
 #ifndef XP_MACOSX
   // Windowed plugins should not be calling NPN_InvalidateRect, but
@@ -664,16 +663,7 @@ NS_IMETHODIMP nsPluginInstanceOwner::InvalidateRect(NPRect *invalidRect)
               presContext->DevPixelsToAppUnits(invalidRect->top),
               presContext->DevPixelsToAppUnits(invalidRect->right - invalidRect->left),
               presContext->DevPixelsToAppUnits(invalidRect->bottom - invalidRect->top));
-  if (container) {
-    gfxIntSize newSize = container->GetCurrentSize();
-    if (newSize != oldSize) {
-      // The image size has changed - invalidate the old area too, bug 635405.
-      nsRect oldRect = nsRect(0, 0,
-                              presContext->DevPixelsToAppUnits(oldSize.width),
-                              presContext->DevPixelsToAppUnits(oldSize.height));
-      rect.UnionRect(rect, oldRect);
-    }
-  }
+
   rect.MoveBy(mObjectFrame->GetContentRectRelativeToSelf().TopLeft());
   mObjectFrame->InvalidateLayer(rect, nsDisplayItem::TYPE_PLUGIN);
   return NS_OK;