Enable fast/images with slimming paint

Source/core/paint/HTMLCanvasPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/HTMLCanvasPainter.h"
 
 #include "core/html/HTMLCanvasElement.h"
+#include "core/paint/DrawingRecorder.h"
+#include "core/paint/HTMLCanvasClipper.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderHTMLCanvas.h"
 #include "platform/geometry/LayoutPoint.h"
 
 namespace blink {
 
 void HTMLCanvasPainter::paintReplaced(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     GraphicsContext* context = paintInfo.context;
 
     LayoutRect contentRect = m_renderHTMLCanvas.contentBoxRect();
     contentRect.moveBy(paintOffset);
     LayoutRect paintRect = m_renderHTMLCanvas.replacedContentRect();
     paintRect.moveBy(paintOffset);
 
+    PaintInfo localPaintInfo(paintInfo);
+    OwnPtr<HTMLCanvasClipper> clipRecorder;
     bool clip = !contentRect.contains(paintRect);
-    if (clip) {
-        // Not allowed to overflow the content box.
-        paintInfo.context->save();
-        paintInfo.context->clip(pixelSnappedIntRect(contentRect));
-    }
+    if (clip)
+        clipRecorder = adoptPtr(new HTMLCanvasClipper(m_renderHTMLCanvas, paintInfo, contentRect));
 
     // FIXME: InterpolationNone should be used if ImageRenderingOptimizeContrast is set.
     // See bug for more details: crbug.com/353716.
     InterpolationQuality interpolationQuality = m_renderHTMLCanvas.style()->imageRendering() == ImageRenderingOptimizeContrast ? InterpolationLow : CanvasDefaultInterpolationQuality;
 
     HTMLCanvasElement* canvas = toHTMLCanvasElement(m_renderHTMLCanvas.node());
     LayoutSize layoutSize = contentRect.size();
     if (m_renderHTMLCanvas.style()->imageRendering() == ImageRenderingPixelated
         && (layoutSize.width() > canvas->width() || layoutSize.height() > canvas->height() || layoutSize == canvas->size())) {
         interpolationQuality = InterpolationNone;
     }
 
+    DrawingRecorder recorder(context, &m_renderHTMLCanvas, localPaintInfo.phase, pixelSnappedIntRect(paintRect));
     InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
     context->setImageInterpolationQuality(interpolationQuality);
     canvas->paint(context, paintRect);
     context->setImageInterpolationQuality(previousInterpolationQuality);
-
-    if (clip)
-        context->restore();
 }
 
 } // namespace blink