Only communicate CSSPrimitiveValue references from SVGLength

Only communicate CSSPrimitiveValue references from SVGLength

Make asCSSPrimitiveValue() return a reference to a CSSPrimitiveValue,
rather than a pointer. The CSSPrimitiveValue contained in the SVGLength
can/should never be null.
Add a helper to SVGAnimatedLength to cut down on some boilerplate for
accessing the current CSSValue.

Committed: https://crrev.com/2c52d7de8460af29a7f25bb48f59bcf8fb10a93a
Cr-Commit-Position: refs/heads/master@{#435688}

[fs, 2016-12-01 17:43:24]

The CQ bit was checked by fs@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-12-01 17:43:45]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-01 19:21:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-01 19:21:50]

Dry run: This issue passed the CQ dry run.

[fs, 2016-12-01 19:34:55]

fs@opera.com changed reviewers:
+ pdr@chromium.org, schenney@chromium.org

[Stephen Chennney, 2016-12-01 19:41:34]

LGTM

[fs, 2016-12-01 20:04:37]

The CQ bit was checked by fs@opera.com

[commit-bot: I haz the power, 2016-12-01 20:05:04]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-01 20:11:07]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1480622677693750, "parent_rev":
"078fa494619c396c1767d9e8283d7b0447d557bf", "commit_rev":
"ade523828832a878be6f05bdf75fb3d30f996a57"}

[commit-bot: I haz the power, 2016-12-01 20:11:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-12-01 20:13:44]

Description was changed from

==========
Only communicate CSSPrimitiveValue references from SVGLength

Make asCSSPrimitiveValue() return a reference to a CSSPrimitiveValue,
rather than a pointer. The CSSPrimitiveValue contained in the SVGLength
can/should never be null.
Add a helper to SVGAnimatedLength to cut down on some boilerplate for
accessing the current CSSValue.
==========

to

==========
Only communicate CSSPrimitiveValue references from SVGLength

Make asCSSPrimitiveValue() return a reference to a CSSPrimitiveValue,
rather than a pointer. The CSSPrimitiveValue contained in the SVGLength
can/should never be null.
Add a helper to SVGAnimatedLength to cut down on some boilerplate for
accessing the current CSSValue.

Committed: https://crrev.com/2c52d7de8460af29a7f25bb48f59bcf8fb10a93a
Cr-Commit-Position: refs/heads/master@{#435688}
==========

[commit-bot: I haz the power, 2016-12-01 20:13:45]

Patchset 1 (id:??) landed as
https://crrev.com/2c52d7de8460af29a7f25bb48f59bcf8fb10a93a
Cr-Commit-Position: refs/heads/master@{#435688}