Bug 636870 - Using webgl on optimus hardware causes instant crash [part2] (r=jmuizelaar, a=blocker).

widget/src/windows/GfxInfo.cpp

@@ -810,6 +810,15 @@ GfxInfo::GetFeatureStatusImpl(PRInt32 aFeature, PRInt32 *aStatus, nsAString & aS
     return NS_OK;
   }
 
+  // ANGLE currently uses D3D10 <-> D3D9 interop, which crashes on Optimus
+  // machines.
+  if (aFeature == FEATURE_WEBGL_ANGLE &&
+      gfxWindowsPlatform::IsOptimus())
+  {
+    *aStatus = FEATURE_BLOCKED_DEVICE;
+    return NS_OK;
+  }
+
   OperatingSystem os = WindowsVersionToOperatingSystem(mWindowsVersion);
 
   // Windows Server 2003 should be just like Windows XP for present purpose, but still has a different version number.