Fix masking cull rects

Source/core/paint/SVGMaskPainter.cpp

Index: Source/core/paint/SVGMaskPainter.cpp
diff --git a/Source/core/paint/SVGMaskPainter.cpp b/Source/core/paint/SVGMaskPainter.cpp
index d1c326f1571c434d4f592f285ca049d17f201bc1..0e020337927d501bcf5adeb29464412b2efa2905 100644
--- a/Source/core/paint/SVGMaskPainter.cpp
+++ b/Source/core/paint/SVGMaskPainter.cpp
@@ -9,10 +9,8 @@
 #include "core/paint/CompositingRecorder.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
 #include "core/paint/PaintInfo.h"
-#include "core/paint/TransformRecorder.h"
 #include "platform/graphics/paint/CompositingDisplayItem.h"
 #include "platform/graphics/paint/DisplayItemList.h"
-#include "platform/graphics/paint/DrawingDisplayItem.h"
 
 namespace blink {
 
@@ -73,11 +71,13 @@ void SVGMaskPainter::drawMaskForLayoutObject(GraphicsContext* context, const Lay
     AffineTransform contentTransformation;
     RefPtr<const SkPicture> maskContentPicture = m_mask.createContentPicture(contentTransformation, targetBoundingBox);
 
-    TransformRecorder recorder(*context, layoutObject, contentTransformation);
-
-    LayoutObjectDrawingRecorder drawingRecorder(*context, layoutObject, DisplayItem::SVGMask, LayoutRect::infiniteIntRect());

[chrishtr, 2015/06/12 16:03:03]

Curious: why did the infinite rect not work?

-    if (!drawingRecorder.canUseCachedDrawing())
+    LayoutObjectDrawingRecorder drawingRecorder(*context, layoutObject, DisplayItem::SVGMask, targetBoundingBox);

[fs, 2015/06/12 08:12:31]

targetBoundingBox could be too tight - maybe expose m_maskContentBoundaries and
use that? (Or use the paintInvalidationRect from object.)

+    if (!drawingRecorder.canUseCachedDrawing()) {

[fs, 2015/06/12 08:12:31]

Early out?

+        context->save();
+        context->concatCTM(contentTransformation);
         context->drawPicture(maskContentPicture.get());
+        context->restore();
+    }
 }
 
 }