Backed out 2 changesets (bug 1318266) for breaking tab drawing when a LWT is applied.

Backed out changeset 00bb4e2f5a3c (bug 1318266)
Backed out changeset 55790893cab4 (bug 1318266)

layout/painting/FrameLayerBuilder.cpp

@@ -4340,13 +4340,6 @@ ContainerState::ProcessDisplayItems(nsDisplayList* aList)
       } else if (item->GetType() == nsDisplayItem::TYPE_MASK) {
         nsDisplayMask* maskItem = static_cast<nsDisplayMask*>(item);
         SetupMaskLayerForCSSMask(ownLayer, maskItem);
-
-        nsDisplayItem* next = aList->GetBottom();
-        if (next && next->GetType() == nsDisplayItem::TYPE_SCROLL_INFO_LAYER) {
-          // Since we do build a layer for mask, there is no need for this
-          // scroll info layer anymore.
-          aList->RemoveBottom();
-        }
       }
 
       // Convert the visible rect to a region and give the item

layout/painting/nsDisplayList.cpp

@@ -7353,12 +7353,13 @@ bool nsDisplayMask::ShouldPaintOnMaskLayer(LayerManager* aManager)
   nsSVGUtils::MaskUsage maskUsage;
   nsSVGUtils::DetermineMaskUsage(mFrame, mHandleOpacity, maskUsage);
 
-  if (!maskUsage.shouldGenerateMaskLayer && !maskUsage.shouldApplyClipPath &&
+  if (!maskUsage.shouldGenerateMaskLayer &&
       !maskUsage.shouldGenerateClipMaskLayer) {
     return false;
   }
 
-  if (maskUsage.opacity != 1.0 || maskUsage.shouldApplyBasicShape) {
+  if (maskUsage.opacity != 1.0 || maskUsage.shouldApplyClipPath ||
+      maskUsage.shouldApplyBasicShape) {
     return false;
   }
 

layout/svg/nsSVGClipPathFrame.cpp

@@ -272,6 +272,8 @@ nsSVGClipPathFrame::GetClipMask(gfxContext& aReferenceContext,
                                 SourceSurface* aExtraMask,
                                 const Matrix& aExtraMasksTransform)
 {
+  MOZ_ASSERT(!IsTrivial(), "Caller needs to use ApplyClipPath");
+
   IntPoint offset;
   RefPtr<DrawTarget> maskDT = CreateClipMask(aReferenceContext, offset);
   if (!maskDT) {

layout/svg/nsSVGIntegrationUtils.cpp

@@ -756,7 +756,6 @@ nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
   nsSVGUtils::DetermineMaskUsage(aParams.frame, aParams.handleOpacity,
                                  maskUsage);
   MOZ_ASSERT(maskUsage.shouldGenerateMaskLayer ||
-             maskUsage.shouldApplyClipPath ||
              maskUsage.shouldGenerateClipMaskLayer);
 
   nsIFrame* frame = aParams.frame;
@@ -798,7 +797,7 @@ nsSVGIntegrationUtils::PaintMask(const PaintFramesParams& aParams)
   }
 
   // Paint clip-path onto ctx.
-  if (maskUsage.shouldGenerateClipMaskLayer || maskUsage.shouldApplyClipPath) {
+  if (maskUsage.shouldGenerateClipMaskLayer) {
     matSR.Restore();
     matSR.SetContext(&ctx);