Merge 181007 "Restore SVG filter optimization that was lost in t..."

Merge 181007 "Restore SVG filter optimization that was lost in t..."

> Restore SVG filter optimization that was lost in the deferral switch.
> 
> The legacy filter path does some optimizations to filter bounds in the
> case where the filter is known not to affect transparent black, or can
> be restricted to a subset of its input rects. Although we should
> probably move these optimizations to Skia in the medium term, for now
> this change simply invokes them from the deferred path as well.
> 
> This caused some minor pixel diffs at the clip boundaries. 
> Since many of these same tests were also affected by an 
> unnecessary snapping to integer pixels (that I've been 
> meaning to remove -- it makes the results worse, and is 
> wrong in the pinch-zoom case anyway), I've removed that
> here as well.
> 
> BUG=408031
> 
> Review URL: https://codereview.chromium.org/498073003

TBR=senorblanco@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181391

[Justin Novosad, 2014-09-04 19:10:24]

Committed patchset #1 (id:1) manually as r181391.