Large canvas does not honor containing div's border radius

Source/core/rendering/RenderReplaced.cpp

Index: Source/core/rendering/RenderReplaced.cpp
diff --git a/Source/core/rendering/RenderReplaced.cpp b/Source/core/rendering/RenderReplaced.cpp
index 93db7ed2d3e54c4cebd894321c8c13bad8d20a4a..bdfa1e82a8e69533c2405fecace4c1c3b06113ab 100644
--- a/Source/core/rendering/RenderReplaced.cpp
+++ b/Source/core/rendering/RenderReplaced.cpp
@@ -120,11 +120,14 @@ void RenderReplaced::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
         return;
     }
 
+    if (paintInfo.phase == PaintPhaseBorderRadiusMask && (!hasLayer() || !layer()->hasCompositedBorderRadiusMask()))
+        return;
+
     LayoutRect paintRect = LayoutRect(adjustedPaintOffset, size());
     if ((paintInfo.phase == PaintPhaseOutline || paintInfo.phase == PaintPhaseSelfOutline) && style()->outlineWidth())
         paintOutline(paintInfo, paintRect);
     
-    if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseSelection && !canHaveChildren())
+    if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseSelection && !canHaveChildren() && paintInfo.phase != PaintPhaseBorderRadiusMask)
         return;
     
     if (!paintInfo.shouldPaintWithinRoot(this))
@@ -153,7 +156,11 @@ void RenderReplaced::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
     }
 
     if (!completelyClippedOut) {
-        paintReplaced(paintInfo, adjustedPaintOffset);
+        if (paintInfo.phase == PaintPhaseBorderRadiusMask) {
+            paintInfo.context->fillRect(pixelSnappedIntRect(paintRect), Color::black);
+        } else {
+            paintReplaced(paintInfo, adjustedPaintOffset);
+        }
 
         if (style()->hasBorderRadius())
             paintInfo.context->restore();
@@ -171,7 +178,7 @@ void RenderReplaced::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 bool RenderReplaced::shouldPaint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseOutline && paintInfo.phase != PaintPhaseSelfOutline 
-            && paintInfo.phase != PaintPhaseSelection && paintInfo.phase != PaintPhaseMask)
+            && paintInfo.phase != PaintPhaseSelection && paintInfo.phase != PaintPhaseMask && paintInfo.phase != PaintPhaseBorderRadiusMask)
         return false;
 
     if (!paintInfo.shouldPaintWithinRoot(this))