Fix incorrectly disabled SSE2 WebAudio optimizations for Windows.

Fix incorrectly disabled SSE2 WebAudio optimizations for Windows.

MSVC doesn't set __SSE__ or__SSE2__ defines:

http://msdn.microsoft.com/en-us/library/b0084kay.aspx

BUG=349320
TEST=compiles

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=175173

[Raymond Toy, 2014-05-29 23:13:35]

lgtm overall, but are we certain that all x86 platforms will now run with SSE2? 
If so, that is fantastic, and there are a few other places that need to be fixed
for Windows. (In a different CL.)

[DaleCurtis, 2014-05-29 23:19:57]

Yes, that's my understanding.  OSX is already like SSSE3 and Linux and Windows
are now SSE2+.

[DaleCurtis, 2014-05-29 23:20:26]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-05-29 23:22:24]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/307963005/1

[commit-bot: I haz the power, 2014-05-30 14:37:27]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/1...)
  linux_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/1...)
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/9926)

[commit-bot: I haz the power, 2014-05-30 15:18:17]

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

[commit-bot: I haz the power, 2014-05-30 15:18:17]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/1...)

[Raymond Toy, 2014-05-30 16:12:33]

On 2014/05/30 15:18:17, I haz the power (commit-bot) wrote:
> Try jobs failed on following builders:
>   linux_blink_rel on tryserver.blink
>
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/1...)

I guess this isn't a surprise that enabling sse2 on linux breaks some of the
webaudio layout tests.

[DaleCurtis, 2014-05-30 17:07:35]

Hmm, I'll see if I can rebaseline in this CL too.

[DaleCurtis, 2014-05-30 18:43:44]

PTAL.  Turns out I actually disabled SSE on x64 which is what caused Linux to
break.  Only Windows should have broken.

[Raymond Toy, 2014-05-30 18:46:58]

lgtm

[DaleCurtis, 2014-05-30 19:40:49]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-05-30 19:42:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/307963005/20001

[commit-bot: I haz the power, 2014-05-30 22:35:53]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/10006)

[commit-bot: I haz the power, 2014-05-30 23:36:37]

Change committed as 175173