Fix support for GL_MAX_ATTRIBS attributes.

*re-land with fix for AMD/ES2/OpenGL.*

An off-by-one bug slipped in that broke support for these edge case
shaders.

Bug introduced in https://chromium-review.googlesource.com/#/c/266928/

BUG=angleproject:1045
BUG=500116

Change-Id: If44f809d432221d1e17afc407d49e87e0cb7504c
Reviewed-on: https://chromium-review.googlesource.com/277664
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/Program.cpp b/src/libANGLE/Program.cpp
index da4d609..dd5ec95 100644
--- a/src/libANGLE/Program.cpp
+++ b/src/libANGLE/Program.cpp
@@ -1291,7 +1291,7 @@
     GLuint maxAttribs = data.caps->maxVertexAttributes;
 
     // TODO(jmadill): handle aliasing robustly
-    if (shaderAttributes.size() >= maxAttribs)
+    if (shaderAttributes.size() > maxAttribs)
     {
         infoLog << "Too many vertex attributes.";
         return false;