Move CSS image filters to the deferred path.

This changes CSS image filter rendering on the software 
path to use the deferred (Skia) path. This fixes HiDPI 
and pinch-zoom of filter effects, since the filter 
content is now captured in the main SkPicture, and 
plays back with the appropriate matrix by the compositor.

Several of the reference filter tests changed 
significantly, but the new results are closer to 
the accelerated path, and closer to Firefox. This is 
because the coordinate space origin and clipping in 
the old path was incorrect.

Some other tests have minor pixel diffs.

BUG=403557,362508,237641,156019

Review URL: https://codereview.chromium.org/469113002

git-svn-id: svn://svn.chromium.org/blink/trunk@180693 bbb929c8-8fbe-4397-9dbb-9b2b20218538