Bug 1450403. blob-invalidation: hookup paint flashing. r=mstange

--HG--
extra : rebase_source : 70c84041e3987677c40ce617d442d1ea36b86b1a

gfx/layers/wr/WebRenderCommandBuilder.cpp

@@ -586,12 +586,13 @@ struct DIGroup
 
     PaintItemRange(aGrouper, aStartItem, aEndItem, context, recorder);
 
-    if (!mKey) {
-#if 0
+    if (aStartItem->Frame()->PresContext()->GetPaintFlashing()) {
       context->SetMatrix(Matrix());
-      dt->FillRect(gfx::Rect(0, 0, size.width, size.height), gfx::ColorPattern(gfx::Color(0., 1., 0., 0.5)));
+      float r = float(rand()) / RAND_MAX;
+      float g = float(rand()) / RAND_MAX;
+      float b = float(rand()) / RAND_MAX;
+      dt->FillRect(gfx::Rect(0, 0, size.width, size.height), gfx::ColorPattern(gfx::Color(r, g, b, 0.5)));
       dt->FlushItem(IntRect(IntPoint(0, 0), size));
-#endif
     }
 
     // XXX: set this correctly perhaps using aItem->GetOpaqueRegion(aDisplayListBuilder, &snapped).Contains(paintBounds);?