ES31: Add std430 support for OpenGL backend

BUG=angleproject:1920
TEST=angle_unittests

Change-Id: Ie8e171abec053c2c5dca93d6e79db534f74520e7
Reviewed-on: https://chromium-review.googlesource.com/737532
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/renderer/d3d/ProgramD3D.cpp b/src/libANGLE/renderer/d3d/ProgramD3D.cpp
index 6bb92b0..9c633b0 100644
--- a/src/libANGLE/renderer/d3d/ProgramD3D.cpp
+++ b/src/libANGLE/renderer/d3d/ProgramD3D.cpp
@@ -2276,7 +2276,7 @@
     sh::HLSLBlockEncoder hlslEncoder(sh::HLSLBlockEncoder::ENCODE_PACKED, false);
     sh::BlockLayoutEncoder *encoder = nullptr;
 
-    if (interfaceBlock.layout == sh::BLOCKLAYOUT_STANDARD)
+    if (interfaceBlock.layout == sh::BLOCKLAYOUT_STD140)
     {
         encoder = &std140Encoder;
     }