Require 8 stencil bits in the BlitFramebufferANGLETest.

The test can fail if it uses a config where the default framebuffer does
not have a stencil buffer.

BUG=angle:658

Change-Id: I82eaf5b508182514439e69469e77591e1aceaf66
Reviewed-on: https://chromium-review.googlesource.com/246461
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/tests/angle_tests/BlitFramebufferANGLETest.cpp b/tests/angle_tests/BlitFramebufferANGLETest.cpp
index a4cec71..85a8a43 100644
--- a/tests/angle_tests/BlitFramebufferANGLETest.cpp
+++ b/tests/angle_tests/BlitFramebufferANGLETest.cpp
@@ -16,6 +16,7 @@
         setConfigBlueBits(8);
         setConfigAlphaBits(8);
         setConfigDepthBits(24);
+        setConfigStencilBits(8);
 
         mCheckerProgram = 0;
         mBlueProgram = 0;