Avoid false-positives of under-invalidation checking

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/layout/LayoutHTMLCanvas.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
 #include "core/paint/PaintInfo.h"
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/graphics/paint/ClipRecorder.h"
 
 namespace blink {
 
 void HTMLCanvasPainter::paintReplaced(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     GraphicsContext* context = paintInfo.context;
 
     LayoutRect contentRect = m_layoutHTMLCanvas.contentBoxRect();
     contentRect.moveBy(paintOffset);
     LayoutRect paintRect = m_layoutHTMLCanvas.replacedContentRect();
     paintRect.moveBy(paintOffset);
 
     LayoutObjectDrawingRecorder drawingRecorder(*context, m_layoutHTMLCanvas, paintInfo.phase, contentRect);
     if (drawingRecorder.canUseCachedDrawing())
         return;
 
+#if ENABLE(ASSERT)
+    // The drawing may be in display list mode or image mode, producing different pictures for the same result.
+    drawingRecorder.setUnderInvalidationCheckingMode(DrawingDisplayItem::CheckBitmap);
+#endif
+
     bool clip = !contentRect.contains(paintRect);
     if (clip) {
         context->save();
         context->clip(contentRect);
     }
 
     // FIXME: InterpolationNone should be used if ImageRenderingOptimizeContrast is set.
     // See bug for more details: crbug.com/353716.
     InterpolationQuality interpolationQuality = m_layoutHTMLCanvas.style()->imageRendering() == ImageRenderingOptimizeContrast ? InterpolationLow : CanvasDefaultInterpolationQuality;
     if (m_layoutHTMLCanvas.style()->imageRendering() == ImageRenderingPixelated)
         interpolationQuality = InterpolationNone;
 
     InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
     context->setImageInterpolationQuality(interpolationQuality);
     toHTMLCanvasElement(m_layoutHTMLCanvas.node())->paint(context, paintRect);
     context->setImageInterpolationQuality(previousInterpolationQuality);
 
     if (clip)
         context->restore();
 }
 
 } // namespace blink