Attempt to fix issue 344300 by guarding against rootStyle being null.

Attempt to fix issue 344300 by guarding against rootStyle being null.

From what I can tell this was introduced in issue 64293008 at Nov 29th 2013. Clusterfuzz also broke at that time with a similar stack trace. 

An alternatively fix could be to assert that rootStyle is never set to null in the constructors of CSSToLengthConversionData. However that seems to be a more involved fix and I will leave that for the owner of the code.

R=ager@chromium.org, erik.corry@gmail.com, haraken@chromium.org, timloh@chromium.org, tkent@chromium.org, vegorov@chromium.org, zerny@chromium.org
BUG=344300
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=167596

[Timothy Loh, 2014-02-20 05:26:23]

lgtm (I'm not an OWNER), this is probably fine for now. I guess this is just the
case of starting a pseudo-element animation with rems immediately? We probably
should make sure that the root style is properly passed through, but I suspect
this never worked and probably isn't too important.

[esprehn, 2014-02-20 07:05:24]

not lgtm, you need to add a test.

[wibling-chromium, 2014-02-20 12:59:19]

On 2014/02/20 07:05:24, esprehn wrote:
> not lgtm, you need to add a test.

Okay. I will look into that.

[wibling-chromium, 2014-02-20 14:17:46]

PTAL

The added test crashes chromium without the patch.

[rune, 2014-02-20 14:28:27]

On 2014/02/20 14:17:46, wibling-chromium wrote:
> PTAL
> 
> The added test crashes chromium without the patch.

You should avoid png and render tree dumps as they will be platform specific
when they include text. A dumpAsText test should suffice here.

[wibling-chromium, 2014-02-20 14:39:57]

On 2014/02/20 14:28:27, rune - CET wrote:
> On 2014/02/20 14:17:46, wibling-chromium wrote:
> > PTAL
> > 
> > The added test crashes chromium without the patch.
> 
> You should avoid png and render tree dumps as they will be platform specific
> when they include text. A dumpAsText test should suffice here.

Will do. New diff coming up.

[wibling-chromium, 2014-02-20 14:42:16]

PTAL

[ojan, 2014-02-20 20:23:41]

lgtm

I agree with the change description that a better fix would be to figure out why
the rootStyle can be null, but since this is just reverting part of
https://codereview.chromium.org/64293008/, I think this fix is fine.

Thanks!

[commit-bot: I haz the power, 2014-02-20 20:23:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wibling@chromium.org/170283003/180001

[commit-bot: I haz the power, 2014-02-21 00:19:43]

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

[commit-bot: I haz the power, 2014-02-21 00:19:44]

Retried try job too often on linux_blink for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_blin...

[wibling-chromium, 2014-02-21 08:27:25]

The CQ bit was checked by wibling@chromium.org

[commit-bot: I haz the power, 2014-02-21 08:27:40]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wibling@chromium.org/170283003/180001

[commit-bot: I haz the power, 2014-02-21 11:42:05]

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

[commit-bot: I haz the power, 2014-02-21 11:42:05]

Retried try job too often on linux_blink for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_blin...

[wibling-chromium, 2014-02-21 11:43:31]

The CQ bit was checked by wibling@chromium.org

[commit-bot: I haz the power, 2014-02-21 11:43:37]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wibling@chromium.org/170283003/180001

[commit-bot: I haz the power, 2014-02-21 13:59:21]

Change committed as 167596