Bug 648484, part E: Hook d3d9 shadow layers up to new system. r=BenWa

gfx/layers/d3d9/LayerManagerD3D9.h

@@ -121,6 +121,9 @@ public:
    */
   virtual void Destroy();
 
+  virtual ShadowLayerManager* AsShadowManager()
+  { return this; }
+
   virtual void BeginTransaction();
 
   virtual void BeginTransactionWithTarget(gfxContext* aTarget);

layout/ipc/RenderFrameParent.cpp

@@ -731,7 +731,7 @@ RenderFrameParent::AllocPLayers(LayerManager::LayersBackend* aBackendType)
   LayerManager* lm = GetLayerManager();
   ShadowLayerManager* slm = lm->AsShadowManager();
   if (!slm) {
-     NS_WARNING("shadow layers no sprechen D3D backend yet");
+    *aBackendType = LayerManager::LAYERS_NONE;
      return nsnull;
   }
   *aBackendType = lm->GetBackendType();