Remove 2 calls to paintInvalidationForWholeRenderer

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 6888e7414ac5bfae5e8e208e300fa0d4aed80015..96e748845c4494b1d04def40fe6948bdac382366 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -142,12 +142,7 @@ void RenderBox::styleWillChange(StyleDifference diff, const RenderStyle& newStyl
 {
     RenderStyle* oldStyle = style();
     if (oldStyle) {
-        // The background of the root element or the body element could propagate up to
-        // the canvas.  Just dirty the entire canvas when our style changes substantially.
-        if ((diff.needsRepaint() || diff.needsLayout()) && node()
-            && (isHTMLHtmlElement(*node()) || isHTMLBodyElement(*node()))) {
-            view()->paintInvalidationForWholeRenderer();
-
+        if ((diff.needsRepaint() || diff.needsLayout()) && backgroundCanBleedToCanvas()) {
             if (oldStyle->hasEntirelyFixedBackground() != newStyle.hasEntirelyFixedBackground())
                 view()->compositor()->setNeedsUpdateFixedBackground();
         }
@@ -163,10 +158,6 @@ void RenderBox::styleWillChange(StyleDifference diff, const RenderStyle& newStyl
             if (isFloating() && !isOutOfFlowPositioned() && newStyle.hasOutOfFlowPosition())
                 removeFloatingOrPositionedChildFromBlockLists();
         }
-    // FIXME: This branch runs when !oldStyle, which means that layout was never called
-    // so what's the point in invalidating the whole view that we never painted?
-    } else if (isBody()) {
-        view()->paintInvalidationForWholeRenderer();
     }
 
     RenderBoxModelObject::styleWillChange(diff, newStyle);
@@ -1961,6 +1952,13 @@ LayoutRect RenderBox::clippedOverflowRectForPaintInvalidation(const RenderLayerM
     if (style()->visibility() != VISIBLE && enclosingLayer()->subtreeIsInvisible())
         return LayoutRect();
 
+    // If we have a background that could bleed into the canvas, just return
+    // the viewport's rectangle. This works as only body and the document
+    // element's renderer can bleed into the viewport so we are guaranteed
+    // to be in the RenderView's coordinate space.
+    if (style()->hasBackground() && backgroundCanBleedToCanvas())
+        return view()->viewRect();

[dsinclair, 2014/07/21 19:32:28]

Should we add an ASSERT here just to be safe that we're body or html? Not sure
if it would happen, but we could potentially expand the meaning of
backgroundCanBleedToCanvas in the future.

[Julien - ping for review, 2014/07/21 20:33:33]

I don't think that would give us much as that's the definition of
backgroundCanBleedToCanvas and I don't think this definition will evolve (this
is an old HTML concept). If we did evolve it, I would expect hackers / reviewers
to check this comment.

+
     LayoutRect r = visualOverflowRect();
     mapRectToPaintInvalidationBacking(paintInvalidationContainer, r, false /*fixed*/, paintInvalidationState);
     return r;