Reinstate workarounds for atan2, fmod, pow in MathExtras on vs2013

Reinstate workarounds for atan2, fmod, pow in MathExtras on vs2013

I incorrectly removed some these workaround functions for VS2013 at
https://codereview.chromium.org/27009003 . The other non-workaround
functions (that just didn't exist previously) seem to be OK, but the
behaviour around +-Inf is still different than we expect for JS and
XPath.

R=jamesr@chromium.org
BUG=347870
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168231

[jamesr, 2014-02-28 23:04:49]

can we add unit tests for these math cases in MathExtrasTest.cpp ? since you
know the cases to hit and can test vs2013, presumably you'd be in a good spot to
add these?

[jamesr, 2014-02-28 23:05:08]

lgtm if you pinky swear to add tests for each of these workarounds soon

[scottmg, 2014-02-28 23:06:12]

On 2014/02/28 23:05:08, jamesr wrote:
> lgtm if you pinky swear to add tests for each of these workarounds soon

OK, I'll land this now so I can hopefully get the switch done tonight, and work
on unittests now.

[scottmg, 2014-02-28 23:06:14]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2014-02-28 23:06:25]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/scottmg@chromium.org/184103006/1

[scottmg, 2014-02-28 23:18:29]

The CQ bit was unchecked by scottmg@chromium.org

[scottmg, 2014-02-28 23:19:10]

nvm, added tests here, ptal

[jamesr, 2014-02-28 23:32:06]

still lgtm. i hope we don't need fuzzy comparisons on these

[scottmg, 2014-03-01 02:37:43]

Committed patchset #2 manually as r168231 (presubmit successful).