Make compositingState explicit

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 040172a33d8eec668267888fdb603f808f30275f..71f92e6ca3c1fc76bad44992491bdd497ae7780a 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -1236,7 +1236,8 @@ static bool isCandidateForOpaquenessTest(RenderBox* childBox)
     if (!childBox->width() || !childBox->height())
         return false;
     if (RenderLayer* childLayer = childBox->layer()) {
-        if (childLayer->isComposited())
+        // FIXME: perhaps this could be less conservative?
+        if (childLayer->compositingState() != NotComposited)
             return false;
         // FIXME: Deal with z-index.
         if (!childStyle->hasAutoZIndex())
@@ -1331,7 +1332,7 @@ void RenderBox::paintClippingMask(PaintInfo& paintInfo, const LayoutPoint& paint
     if (!paintInfo.shouldPaintWithinRoot(this) || style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseClippingMask || paintInfo.context->paintingDisabled())
         return;
 
-    if (!layer() || !layer()->isComposited())
+    if (!layer() || layer()->compositingState() != PaintsIntoOwnBacking)
         return;
 
     LayoutRect paintRect = LayoutRect(paintOffset, size());