Bug 1186426. Avoid using D3D11 ANGLE on systems that require recreating the rendertargetview. r=jgilbert

It turns out I accidentally landed
https://bug1109718.bmoattachments.org/attachment.cgi?id=8630177 as part of
another change. This should avoid the brokeness that was caused by that and
allow us to simplify our changes to ANGLE.

gfx/thebes/gfxWindowsPlatform.cpp

@@ -1793,6 +1793,7 @@ void CheckIfRenderTargetViewNeedsRecreating(ID3D11Device *device)
     // match the clear
     if (resultColor != 0xffffff00) {
         gfxCriticalNote << "RenderTargetViewNeedsRecreating";
+        gANGLESupportsD3D11 = false;
     }
 
     keyedMutex->ReleaseSync(0);