D3D: Use angle::Result error pattern.

This completes the refactor for the D3D9/D3D11 back-ends.

Bug: angleproject:2752
Change-Id: Ie35a925f75c902d8f9fdab6bc33b3bb9c937f85b
Reviewed-on: https://chromium-review.googlesource.com/1167209
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
index b443f9a..8c5e92e 100644
--- a/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
+++ b/src/libANGLE/renderer/d3d/FramebufferD3D.cpp
@@ -401,8 +401,7 @@
 
             gl::Texture *dummyTex = nullptr;
             // TODO(Jamie): Handle error if dummy texture can't be created.
-            ANGLE_SWALLOW_ERR(
-                mRenderer->getIncompleteTexture(context, gl::TextureType::_2D, &dummyTex));
+            (void)mRenderer->getIncompleteTexture(context, gl::TextureType::_2D, &dummyTex);
             if (dummyTex)
             {