Bug 473398. nsCSSRendering::PaintBackground should not try to fix up the canvas background color to be opaque. r+sr=roc

--HG--
extra : rebase_source : f2883c704bee9a4ba70c57598704ed7ba30628dc

layout/base/nsCSSRendering.cpp

@@ -1159,7 +1159,6 @@ nsCSSRendering::PaintBackground(nsPresContext* aPresContext,
 
   PRBool isCanvas;
   const nsStyleBackground *color;
-  const nsStyleBorder* border = aForFrame->GetStyleBorder();
 
   if (!FindBackground(aPresContext, aForFrame, &color, &isCanvas)) {
     // we don't want to bail out of moz-appearance is set on a root
@@ -1178,40 +1177,16 @@ nsCSSRendering::PaintBackground(nsPresContext* aPresContext,
         
     color = aForFrame->GetStyleBackground();
   }
-  if (!isCanvas) {
+
-    PaintBackgroundWithSC(aPresContext, aRenderingContext, aForFrame,
+  if (isCanvas && NS_GET_A(color->mBackgroundColor) == 255) {
-                          aDirtyRect, aBorderArea, *color, *border,
+    nsIViewManager* vm = aPresContext->GetViewManager();
-                          aUsePrintSettings, aBGClipRect);
+    vm->SetDefaultBackgroundColor(color->mBackgroundColor);
-    return;
   }
 
-  nsStyleBackground canvasColor(*color);
-
-  nsIViewManager* vm = aPresContext->GetViewManager();
-
-  if (NS_GET_A(canvasColor.mBackgroundColor) < 255) {
-    // If the window is intended to be opaque, ensure that we always
-    // paint an opaque color for its root element, in case there's no
-    // background at all or a partly transparent image.
-    nsIView* rView;
-    vm->GetRootView(rView);
-    if (!rView->GetParent() &&
-        (!rView->HasWidget() ||
-         rView->GetWidget()->GetTransparencyMode() == eTransparencyOpaque)) {
-      nscolor backColor = aPresContext->DefaultBackgroundColor();
-      NS_ASSERTION(NS_GET_A(backColor) == 255,
-                   "default background color is not opaque");
-
-      canvasColor.mBackgroundColor =
-        NS_ComposeColors(backColor, canvasColor.mBackgroundColor);
-    }
-  }
-
-  vm->SetDefaultBackgroundColor(canvasColor.mBackgroundColor);
-
   PaintBackgroundWithSC(aPresContext, aRenderingContext, aForFrame,
-                        aDirtyRect, aBorderArea, canvasColor,
+                        aDirtyRect, aBorderArea, *color,
-                        *border, aUsePrintSettings, aBGClipRect);
+                        *aForFrame->GetStyleBorder(),
+                        aUsePrintSettings, aBGClipRect);
 }
 
 static PRBool