Implement Color Filters for SKIA SVG backend

Implement color filters for SKIA SVG Backend using SkColorFilter object in SkPaint.
Color filter is applied using the combination of feFlood and feComposite SVG primitives.
This change only implements blend mode kSrcIn in SkBlendMode object.

R=fmalita@chromium.org

Bug: skia::7914
Change-Id: I0b0dcaf72b654b8ba7f1fd7de52141decfdf17b6
Reviewed-on: https://skia-review.googlesource.com/142986
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed