To do this, taint the source graphic of a canvas input to filters if it
is cross-origin.

Bug: 778506
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I7e070c887dbb8bfce64f660790d58836f5d75762
Reviewed-on: https://chromium-review.googlesource.com/782649
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#522143}