Use StyleColor for the flood-color and lighting-color properties

This changes the _interface_ to these properties in ComputedStyle
(and SVGComputedStyle) to use StyleColor - storage is changed to
a <Color, bool> (separated) pair. Usage is updated accordingly.
This is needed in order to support "better" tainting on 'feFlood'
and other filter primitive elements to which these properties apply.
The actual tainting functions will be updated in a follow-up CL.

Bug: 792518
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I705ee38219615c4c691e4a5fbc73799a72b604da
Reviewed-on: https://chromium-review.googlesource.com/797271
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593438}
15 files changed