[Blending and compositing] Implement the isolation CSS property in software

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index 7fa7062c23b747bf03fbb5c5a4c31774b1df7b62..8634b5115c19d1267156435367fcd2e7b650c8c1 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -573,6 +573,8 @@ public:
 
     bool hasBlendMode() const;
 
+    bool hasIsolation() const;
+
     inline bool preservesNewline() const;
 
     // The pseudo element style can be cached or uncached.  Use the cached method if the pseudo element doesn't respect
@@ -959,7 +961,7 @@ public:
     void getTransformFromContainer(const RenderObject* container, const LayoutSize& offsetInContainer, TransformationMatrix&) const;
 
     // return true if this object requires a new stacking context
-    bool createsGroup() const { return isTransparent() || hasMask() || hasFilter() || hasBlendMode(); }
+    bool createsGroup() const { return isTransparent() || hasMask() || hasFilter() || hasBlendMode() || hasIsolation(); }
 
     virtual void addFocusRingRects(Vector<IntRect>&, const LayoutPoint& /* additionalOffset */, const RenderLayerModelObject* /* paintContainer */ = 0) { };