Fix support for GL_MAX_ATTRIBS attributes.

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: Iddfe0c21bef3c3a61017ba56d9e1fc001c0a3703
Reviewed-on: https://chromium-review.googlesource.com/277476
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@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;