Suppress some no-op GraphicsContext calls

Source/platform/graphics/GraphicsContext.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 447 matching lines @@
     realizeSave(SkCanvas::kMatrix_SaveFlag);
 
     m_canvas->setMatrix(matrix);
 }
 
 bool GraphicsContext::concat(const SkMatrix& matrix)
 {
     if (paintingDisabled())
         return false;
 
+    if (matrix.isIdentity())
+        return true;
+
     realizeSave(SkCanvas::kMatrix_SaveFlag);
 
     return m_canvas->concat(matrix);
 }
 
 void GraphicsContext::beginTransparencyLayer(float opacity, const FloatRect* bounds)
 {
     beginLayer(opacity, m_state->m_compositeOperator, bounds);
 }
 
@@ skipping 77 matching lines @@
 
 bool GraphicsContext::isRecording() const
 {
     return !m_recordingStateStack.isEmpty();
 }
 
 void GraphicsContext::drawDisplayList(DisplayList* displayList)
 {
     ASSERT(!displayList->picture()->getRecordingCanvas());
 
-    if (paintingDisabled() || !displayList)
+    if (paintingDisabled() || !displayList || displayList->bounds().isEmpty())
         return;
 
     realizeSave(SkCanvas::kMatrixClip_SaveFlag);
 
     const FloatRect& bounds = displayList->bounds();
     if (bounds.x() || bounds.y())
         m_canvas->translate(bounds.x(), bounds.y());
 
     m_canvas->drawPicture(*displayList->picture());
 
@@ skipping 1004 matching lines @@
     realizeSave(SkCanvas::kMatrix_SaveFlag);
 
     m_canvas->rotate(WebCoreFloatToSkScalar(angleInRadians * (180.0f / 3.14159265f)));
 }
 
 void GraphicsContext::translate(float w, float h)
 {
     if (paintingDisabled())
         return;
 
+    if (!w && !h)
+        return;
+
     realizeSave(SkCanvas::kMatrix_SaveFlag);
 
     m_canvas->translate(WebCoreFloatToSkScalar(w), WebCoreFloatToSkScalar(h));
 }
 
 void GraphicsContext::scale(const FloatSize& size)
 {
     if (paintingDisabled())
         return;
 
+    if (size.width() == 1 && size.height() == 1)

[Stephen Chennney, 2014/01/17 21:53:21]

Not sure if the compiler automatically casts the 1 to 1.0f, but I feel more
comfortable with explicitly saying 1.0f.

+        return;
+
     realizeSave(SkCanvas::kMatrix_SaveFlag);
 
     m_canvas->scale(WebCoreFloatToSkScalar(size.width()), WebCoreFloatToSkScalar(size.height()));
 }
 
 void GraphicsContext::setURLForRect(const KURL& link, const IntRect& destRect)
 {
     if (paintingDisabled())
         return;
 
@@ skipping 385 matching lines @@
 
 void GraphicsContext::didDrawTextInRect(const SkRect& textRect)
 {
     if (m_trackTextRegion) {
         TRACE_EVENT0("skia", "PlatformContextSkia::trackTextRegion");
         m_textRegion.join(textRect);
     }
 }
 
 }