Draw thin slices of an image w/ anti-aliasing for 2D <canvas>

Source/platform/graphics/GraphicsContext.h

Index: Source/platform/graphics/GraphicsContext.h
diff --git a/Source/platform/graphics/GraphicsContext.h b/Source/platform/graphics/GraphicsContext.h
index add6d3c26e59a1e6324dce9fc15eb4094038e3fd..8e275abf629d37a0e5b73a6427e0607528f9345b 100644
--- a/Source/platform/graphics/GraphicsContext.h
+++ b/Source/platform/graphics/GraphicsContext.h
@@ -136,6 +136,13 @@ public:
     void setShouldAntialias(bool antialias) { mutableState()->setShouldAntialias(antialias); }
     bool shouldAntialias() const { return immutableState()->shouldAntialias(); }
 
+    // Disable the anti-aliasing optimization for scales/multiple-of-90-degrees
+    // rotations of thin ("hairline") images.
+    // Note: This will only be reliable when the device pixel scale/ratio is
+    // fixed (e.g. when drawing to context backed by an ImageBuffer).
+    void disableAntialiasingOptimizationForHairlineImages() { ASSERT(!isRecording()); m_antialiasHairlineImages = true; }
+    bool shouldAntialiasHairlineImages() const { return m_antialiasHairlineImages; }
+
     void setShouldClampToSourceRect(bool clampToSourceRect) { mutableState()->setShouldClampToSourceRect(clampToSourceRect); }
     bool shouldClampToSourceRect() const { return immutableState()->shouldClampToSourceRect(); }
 
@@ -504,6 +511,7 @@ private:
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
+    bool m_antialiasHairlineImages : 1;
 };
 
 } // namespace WebCore