Don't coerce pointers to compositor layer mappings to booleans.

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 6e9369ab684efe0235cfed936d466a7445fb15c7..90ac58bf20ef21fc50aa88a4718c344aafbbdf24 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -2077,7 +2077,7 @@ bool FrameView::isTransparent() const
 void FrameView::setTransparent(bool isTransparent)
 {
     m_isTransparent = isTransparent;
-    if (renderView() && renderView()->layer()->compositedLayerMapping())
+    if (renderView() && renderView()->layer()->compositingState() == PaintsIntoOwnBacking)
         renderView()->layer()->compositedLayerMapping()->updateContentsOpaque();
 }
 
@@ -2098,7 +2098,8 @@ void FrameView::setBaseBackgroundColor(const Color& backgroundColor)
     else
         m_baseBackgroundColor = backgroundColor;
 
-    if (CompositedLayerMapping* compositedLayerMapping = renderView() ? renderView()->layer()->compositedLayerMapping() : 0) {
+    if (renderView() && renderView()->layer()->compositingState() == PaintsIntoOwnBacking) {
+        CompositedLayerMappingPtr compositedLayerMapping = renderView()->layer()->compositedLayerMapping();
         compositedLayerMapping->updateContentsOpaque();
         if (compositedLayerMapping->mainGraphicsLayer())
             compositedLayerMapping->mainGraphicsLayer()->setNeedsDisplay();