Make the compositing assert disabler for paint invalidation more targeted.

Source/web/WebPluginContainerImpl.cpp

Index: Source/web/WebPluginContainerImpl.cpp
diff --git a/Source/web/WebPluginContainerImpl.cpp b/Source/web/WebPluginContainerImpl.cpp
index 939d0b31b9827c7bce42271251d015d8da90a85f..e7ff777142ab50298b963df47ce5cbd78ef49939 100644
--- a/Source/web/WebPluginContainerImpl.cpp
+++ b/Source/web/WebPluginContainerImpl.cpp
@@ -141,6 +141,10 @@ void WebPluginContainerImpl::invalidateRect(const IntRect& rect)
     IntRect dirtyRect = rect;
     dirtyRect.move(renderer->borderLeft() + renderer->paddingLeft(),
                    renderer->borderTop() + renderer->paddingTop());
+
+    // For querying RenderLayer::compositingState().
+    // This code should be correct.
+    DisableCompositingQueryAsserts disabler;
     renderer->invalidatePaintRectangle(dirtyRect);
 }