Bug 1189473 - Don't paint the tiles in the APZ minimap. r=mstange

--HG--
extra : commitid : G3omKTHQZtl
extra : rebase_source : 6871b4333cb3c074d9ee85eb7fb3c4ce6236365e

gfx/layers/composite/ContainerLayerComposite.cpp

@@ -471,6 +471,7 @@ RenderMinimap(ContainerT* aContainer, LayerManagerComposite* aManager,
   r = transform.TransformBounds(scrollRect.ToUnknownRect());
   compositor->FillRect(r, backgroundColor, clipRect, aContainer->GetEffectiveTransform());
 
+  /* Disabled because on long pages SlowDrawRect becomes a bottleneck.
   int tileW = gfxPrefs::LayersTileWidth();
   int tileH = gfxPrefs::LayersTileHeight();
 
@@ -484,6 +485,7 @@ RenderMinimap(ContainerT* aContainer, LayerManagerComposite* aManager,
       compositor->SlowDrawRect(r, tileBorderColor, clipRect, aContainer->GetEffectiveTransform());
     }
   }
+  */
 
   r = transform.TransformBounds(scrollRect.ToUnknownRect());
   compositor->SlowDrawRect(r, pageBorderColor, clipRect, aContainer->GetEffectiveTransform());