Disable MRT support when using D3D10 feature levels.

D3D10 cards perform poorly when the pixel shader outputs to multiple
render targets that are not bound.

BUG=325581

Change-Id: I13f6f98861ffeb77cd21f7401ded4425e4ea7841
Reviewed-on: https://chromium-review.googlesource.com/185400
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/190341
diff --git a/src/libGLESv2/renderer/d3d11/Renderer11.cpp b/src/libGLESv2/renderer/d3d11/Renderer11.cpp
index 2c906b6..8e881ca 100644
--- a/src/libGLESv2/renderer/d3d11/Renderer11.cpp
+++ b/src/libGLESv2/renderer/d3d11/Renderer11.cpp
@@ -2482,7 +2482,10 @@
         return D3D11_SIMULTANEOUS_RENDER_TARGET_COUNT;  // 8
       case D3D_FEATURE_LEVEL_10_1:
       case D3D_FEATURE_LEVEL_10_0:
-        return D3D10_SIMULTANEOUS_RENDER_TARGET_COUNT;  // 8
+        // Feature level 10.0 and 10.1 cards perform very poorly when the pixel shader
+        // outputs to multiple RTs that are not bound.
+        // TODO: Remove pixel shader outputs for render targets that are not bound.
+        return 1;
       default:
         UNREACHABLE();
         return 1;