Update bug references for some failing SVG WPT tests

These tests fail because of lack of support for references to general
shapes from <textPath> and the 'side' attribute in <textPath>.
crbug.com/366559 is the bug for supporting thos features, so redirect to
it.

Tests:

  external/wpt/svg/shapes/reftests/pathlength-003.svg
  external/wpt/svg/text/reftests/textpath-side-001.svg
  external/wpt/svg/text/reftests/textpath-shape-001.svg

TBR=schenney@chromium.org
BUG=366559,863355

Change-Id: Ia2fc56704fafd3ace0af949fceeaf2799f960fe7
Reviewed-on: https://chromium-review.googlesource.com/1172298
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#582542}
1 file changed