Introduce Layout*::adjustVisualRectForRasterEffects and use it for SVG hairlines.

third_party/WebKit/Source/core/layout/LayoutObject.h

Index: third_party/WebKit/Source/core/layout/LayoutObject.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.h b/third_party/WebKit/Source/core/layout/LayoutObject.h
index c4cf35150e68a740cc9b2c61775d1e1e8db32475..fb3f525e9f61b806e3a2059916a37747766bc445 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.h
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.h
@@ -1863,6 +1863,11 @@ class CORE_EXPORT LayoutObject : public ImageResourceObserver,
   // changes at all).
   virtual bool anonymousHasStylePropagationOverride() { return false; }
 
+  // Allows objects to adjust |visualEffect|, which is in the space of the
+  // paint invalidation container, for any special raster effects that might
+  // expand the rastered pixel area.
+  virtual void adjustVisualRectForRasterEffects(LayoutRect& visualRect) const {}
+
  protected:
   // This function is called before calling the destructor so that some clean-up
   // can happen regardless of whether they call a virtual function or not. As a