- Re-land with fix for Chromium Debug Windows builds

Chrome forbids RTTI, but standalone ANGLE currently allows it.
Disallowing RTTI in standalone release builds brings ANGLE and Chrome
closer, and prevents accidental use of dynamic_cast in ANGLE.

It also reduces binary size. Win10 libGLESv2 (x86) is 47KB smaller after this.

BUG=angleproject:1239

Change-Id: I505fd0d72868a38444e47198a9bf85ee3e25719f
Reviewed-on: https://chromium-review.googlesource.com/316830
Tryjob-Request: Austin Kinross <aukinros@microsoft.com>
Tested-by: Austin Kinross <aukinros@microsoft.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>