Restore GC state after painting with a "reference" [url(#foo)] clip-path

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 7eb58ff0f355ba051f183de0734dc010f3f212db..8f262b46c2aa22f4a4dd563b5fc33473154273fd 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -1834,7 +1834,7 @@ void RenderLayer::paintLayerContents(GraphicsContext* context, const LayerPainti
     bool rootRelativeBoundsComputed = false;
 
     // Apply clip-path to context.
-    bool hasClipPath = false;
+    GraphicsContextStateSaver clipStateSaver(*context, false);
     RenderStyle* style = renderer()->style();
     RenderSVGResourceClipper* resourceClipper = 0;
     ClipperContext clipperContext;
@@ -1845,8 +1845,7 @@ void RenderLayer::paintLayerContents(GraphicsContext* context, const LayerPainti
     if (renderer()->hasClipPath() && !context->paintingDisabled() && style && (!needsCompositedScrolling() || paintFlags & PaintLayerPaintingChildClippingMaskPhase)) {
         ASSERT(style->clipPath());
         if (style->clipPath()->type() == ClipPathOperation::SHAPE) {
-            hasClipPath = true;
-            context->save();
+            clipStateSaver.save();
             ShapeClipPathOperation* clipPath = toShapeClipPathOperation(style->clipPath());
 
             if (!rootRelativeBoundsComputed) {
@@ -1861,6 +1860,9 @@ void RenderLayer::paintLayerContents(GraphicsContext* context, const LayerPainti
             // FIXME: It doesn't work with forward or external SVG references (https://bugs.webkit.org/show_bug.cgi?id=90405)
             Element* element = document.getElementById(referenceClipPathOperation->fragment());
             if (isSVGClipPathElement(element) && element->renderer()) {
+                // FIXME: Saving at this point is not required in the 'mask'-
+                // case, or if the clip ends up empty.
+                clipStateSaver.save();
                 if (!rootRelativeBoundsComputed) {
                     rootRelativeBounds = physicalBoundingBoxIncludingReflectionAndStackingChildren(paintingInfo.rootLayer, offsetFromRoot);
                     rootRelativeBoundsComputed = true;
@@ -2009,9 +2011,6 @@ void RenderLayer::paintLayerContents(GraphicsContext* context, const LayerPainti
 
     if (resourceClipper)
         resourceClipper->postApplyStatefulResource(renderer(), context, clipperContext);
-
-    if (hasClipPath)
-        context->restore();
 }
 
 void RenderLayer::paintLayerByApplyingTransform(GraphicsContext* context, const LayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags, const LayoutPoint& translationOffset)