Web Animations: Add SVGRectInterpolationType

Web Animations: Add SVGRectInterpolationType

This change migrates the "viewBox" SVG attribute animations over to
SVGRectInterpolationType and enables additive keyframe composite modes
as well as neutral keyframes.

This is a rebased reupload of: https://codereview.chromium.org/1431593004

BUG=530436
Committed: https://crrev.com/5be143be792baea9d6c8328a16a87ee9e74375d5
Cr-Commit-Position: refs/heads/master@{#361294}

[alancutter (OOO until 2018), 2015-11-17 07:17:29]

The CQ bit was checked by alancutter@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-17 07:18:28]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415513010/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415513010/40001

[commit-bot: I haz the power, 2015-11-17 07:22:36]

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

[commit-bot: I haz the power, 2015-11-17 07:22:36]

Dry run: Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_gn_rel on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_gn_r...)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[alancutter (OOO until 2018), 2015-11-18 00:27:14]

The CQ bit was checked by alancutter@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-18 00:27:46]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415513010/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415513010/40001

[commit-bot: I haz the power, 2015-11-18 01:43:35]

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

[commit-bot: I haz the power, 2015-11-18 01:43:35]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[alancutter (OOO until 2018), 2015-11-18 09:13:04]

alancutter@chromium.org changed reviewers:
+ dstockwell@chromium.org, ericwilligers@chromium.org

[Eric Willigers, 2015-11-20 02:18:45]

lgtm

[dstockwell, 2015-11-23 04:54:07]

lgtm

[alancutter (OOO until 2018), 2015-11-23 23:03:40]

The CQ bit was checked by alancutter@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-23 23:09:06]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415513010/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415513010/60001

[commit-bot: I haz the power, 2015-11-24 00:54:45]

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

[commit-bot: I haz the power, 2015-11-24 00:54:46]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[alancutter (OOO until 2018), 2015-11-24 07:17:40]

The CQ bit was checked by alancutter@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-11-24 07:18:45]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415513010/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415513010/60001

[commit-bot: I haz the power, 2015-11-24 08:25:42]

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

[commit-bot: I haz the power, 2015-11-24 08:25:43]

Dry run: This issue passed the CQ dry run.

[alancutter (OOO until 2018), 2015-11-24 08:40:46]

The CQ bit was checked by alancutter@chromium.org

[alancutter (OOO until 2018), 2015-11-24 08:40:46]

The patchset sent to the CQ was uploaded after l-g-t-m from
dstockwell@chromium.org, ericwilligers@chromium.org
Link to the patchset: https://codereview.chromium.org/1415513010/#ps60001
(title: "neutralKeyframe")

[commit-bot: I haz the power, 2015-11-24 08:42:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415513010/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415513010/60001

[commit-bot: I haz the power, 2015-11-24 08:49:25]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-11-24 08:50:31]

Patchset 4 (id:??) landed as
https://crrev.com/5be143be792baea9d6c8328a16a87ee9e74375d5
Cr-Commit-Position: refs/heads/master@{#361294}