Bug 725925 - ShadowableThebesLayer does useless extra composite into 1x1 fake surface. r=cjones

gfx/layers/basic/BasicLayers.cpp

@@ -763,7 +763,9 @@ BasicThebesLayer::PaintThebes(gfxContext* aContext,
   if (BasicManager()->IsTransactionIncomplete())
     return;
 
-  if (!IsHidden()) {
+  gfxRect clipExtents;
+  clipExtents = aContext->GetClipExtents();
+  if (!IsHidden() && !clipExtents.IsEmpty()) {
     AutoSetOperator setOperator(aContext, GetOperator());
     mBuffer.DrawTo(this, aContext, opacity);
   }
@@ -1946,6 +1948,11 @@ BasicLayerManager::PaintLayer(gfxContext* aTarget,
       NS_ABORT_IF_FALSE(untransformedSurface, 
                         "We should always allocate an untransformed surface with 3d transforms!");
 
+      // Temporary fast fix for bug 725886
+      // Revert these changes when 725886 is ready
+      gfxRect clipExtents;
+      clipExtents = aTarget->GetClipExtents();
+      if (!clipExtents.IsEmpty()) {
         gfxPoint offset;
         bool dontBlit = needsClipToVisibleRegion || mTransactionIncomplete ||
                           aLayer->GetEffectiveOpacity() != 1.0f;
@@ -1958,6 +1965,7 @@ BasicLayerManager::PaintLayer(gfxContext* aTarget,
           aTarget->SetSource(result, offset);
         }
       }
+    }
     // If we're doing our own double-buffering, we need to avoid drawing
     // the results of an incomplete transaction to the destination surface ---
     // that could cause flicker. Double-buffering is implemented using a

widget/xpwidgets/PuppetWidget.cpp

@@ -530,6 +530,8 @@ PuppetWidget::DispatchPaintEvent()
       DispatchEvent(&event, status);
     } else {
       nsRefPtr<gfxContext> ctx = new gfxContext(mSurface);
+      ctx->Rectangle(gfxRect(0,0,0,0));
+      ctx->Clip();
       AutoLayerManagerSetup setupLayerManager(this, ctx,
                                               BasicLayerManager::BUFFER_NONE);
       DispatchEvent(&event, status);