Implement clip and scroll DisplayItems for PartPainter

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 405f3d09a4c0829d7b8ace6f4caa564d3f8b124b..8b1712c1e8c31deba82ef61e886136315e75e395 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -84,6 +84,7 @@
 #include "platform/graphics/GraphicsContextStateSaver.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/GraphicsLayerDebugInfo.h"
+#include "platform/graphics/paint/DisplayItemList.h"
 #include "platform/scroll/ScrollAnimator.h"
 #include "platform/text/TextStream.h"
 #include "wtf/CurrentTime.h"
@@ -1387,6 +1388,11 @@ void FrameView::scrollContentsSlowPath(const IntRect& updateRect)
     }
     if (RenderPart* frameRenderer = m_frame->ownerRenderer()) {
         if (isEnclosedInCompositingLayer()) {
+            if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+                RenderView* renderView = this->renderView();
+                ASSERT(renderView);
+                renderView->layer()->enclosingLayerForPaintInvalidationCrossingFrameBoundaries()->graphicsLayerBacking()->displayItemList()->invalidate(renderView->displayItemClient());
+            }

[trchen, 2015/01/22 23:47:57]

FIXME: Currently we always use the cached DisplayItem even if we have a new one.
This will change once https://codereview.chromium.org/847783003/ lands and we
won't need this block anymore.

             LayoutRect rect(frameRenderer->borderLeft() + frameRenderer->paddingLeft(),
                             frameRenderer->borderTop() + frameRenderer->paddingTop(),
                             visibleWidth(), visibleHeight());