Oilpan: revert SVG GC mixin constructor workaround.

Oilpan: revert SVG GC mixin constructor workaround.

Following r191501 (http://crrev.com/980653002), the construction of
a GC mixin object is safe, preventing conservative GCs from going ahead
until the GC mixin object is in a valid state.

With that in place, revert the workaround for SVG mixins (r188695),
which restructured the mixin constructors such that they performed no
heap allocations while the constructed object was in an invalid state.

R=haraken
BUG=420515
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192330

[sof, 2015-03-22 06:34:49]

sigbjornf@opera.com changed reviewers:
+ oilpan-reviews@chromium.org

[sof, 2015-03-22 06:34:50]

please take a look.

[haraken, 2015-03-22 09:11:15]

LGTM

[sof, 2015-03-22 13:58:30]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-03-22 13:58:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1025883002/1

[commit-bot: I haz the power, 2015-03-22 15:35:48]

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

[commit-bot: I haz the power, 2015-03-22 15:35:50]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/5...)

[sof, 2015-03-22 15:52:04]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-03-22 15:52:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1025883002/1

[commit-bot: I haz the power, 2015-03-22 17:33:01]

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

[commit-bot: I haz the power, 2015-03-22 17:33:03]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/5...)

[sof, 2015-03-22 17:44:06]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-03-22 17:44:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1025883002/1

[commit-bot: I haz the power, 2015-03-22 19:22:40]

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

[commit-bot: I haz the power, 2015-03-22 19:22:41]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/5...)

[sof, 2015-03-22 20:47:21]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-03-22 20:47:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1025883002/1

[commit-bot: I haz the power, 2015-03-22 22:25:18]

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

[commit-bot: I haz the power, 2015-03-22 22:25:20]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/5...)

[tkent, 2015-03-23 02:01:11]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2015-03-23 02:01:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1025883002/1

[commit-bot: I haz the power, 2015-03-23 03:18:08]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192330