Handle interpolation of SVG <paint> 'currentColor' w/ Web/CSS Animations

Normalize 'currentColor' to <rgbcolor>, and then interpolate that. This
is similar to how color properties work wrt 'currentColor'.
'currentColor' as a fallback is still left as non-interpolated.

BUG=436772

Review URL: https://codereview.chromium.org/767593002

git-svn-id: svn://svn.chromium.org/blink/trunk@186406 bbb929c8-8fbe-4397-9dbb-9b2b20218538
5 files changed
tree: 3fe4ac23469697d3bf154e495570c13038d69917
  1. third_party/