Use a caps-dependent sized vector to store Uniform Buffers

BUG=angle:685

Change-Id: I3f2e9fcccf27aebbb4ec5485286eec9828851887
Reviewed-on: https://chromium-review.googlesource.com/219805
Tested-by: Shannon Woods <shannonwoods@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libGLESv2/Context.cpp b/src/libGLESv2/Context.cpp
index cf19524..c615c96 100644
--- a/src/libGLESv2/Context.cpp
+++ b/src/libGLESv2/Context.cpp
@@ -91,7 +91,7 @@
     bindRenderbuffer(0);
 
     bindGenericUniformBuffer(0);
-    for (int i = 0; i < IMPLEMENTATION_MAX_COMBINED_SHADER_UNIFORM_BUFFERS; i++)
+    for (unsigned int i = 0; i < mCaps.maxCombinedUniformBlocks; i++)
     {
         bindIndexedUniformBuffer(0, i, 0, -1);
     }