Return the 'active' value for SVGURIReference.href.animVal

Return the 'active' value for SVGURIReference.href.animVal

Make animVal return the currently used ('active') value instead of always
returning that of 'href'.
This should re-establish the former "invariant" that baseVal === animVal
when '(xlink:)href' is not being animated.

BUG=606200
Review URL: https://codereview.chromium.org/1917843002

Cr-Commit-Position: refs/heads/master@{#389490}
(cherry picked from commit 1d488d94b705ce49d710ba9f992f8c31a24c79e0)

Committed: https://chromium.googlesource.com/chromium/src/+/187e748f9e1f2c4bb98fafcee381af8e9b052d1d

[fs, 2016-04-27 11:18:31]

Description was changed from

==========
Return the 'active' value for SVGURIReference.href.animVal

Make animVal return the currently used ('active') value instead of always
returning that of 'href'.
This should re-establish the former "invariant" that baseVal === animVal
when '(xlink:)href' is not being animated.

BUG=606200

Review URL: https://codereview.chromium.org/1917843002

Cr-Commit-Position: refs/heads/master@{#389490}
(cherry picked from commit 1d488d94b705ce49d710ba9f992f8c31a24c79e0)
==========

to

==========
Return the 'active' value for SVGURIReference.href.animVal

Make animVal return the currently used ('active') value instead of always
returning that of 'href'.
This should re-establish the former "invariant" that baseVal === animVal
when '(xlink:)href' is not being animated.

BUG=606200

Review URL: https://codereview.chromium.org/1917843002

Cr-Commit-Position: refs/heads/master@{#389490}
(cherry picked from commit 1d488d94b705ce49d710ba9f992f8c31a24c79e0)

Committed:
https://chromium.googlesource.com/chromium/src/+/187e748f9e1f2c4bb98fafcee381...
==========

[fs, 2016-04-27 11:18:33]

Committed patchset #1 (id:1) manually as
187e748f9e1f2c4bb98fafcee381af8e9b052d1d.