Revert of Initial version of external_oes texture support and unit test

src/gpu/GrResourceProvider.cpp

Index: src/gpu/GrResourceProvider.cpp
diff --git a/src/gpu/GrResourceProvider.cpp b/src/gpu/GrResourceProvider.cpp
index 38213e6266330c9c2e66a4e52bec36ce7e026160..31568144a2ecb01a31152339c403f2cea9e68c9a 100644
--- a/src/gpu/GrResourceProvider.cpp
+++ b/src/gpu/GrResourceProvider.cpp
@@ -202,7 +202,7 @@
         if (rt->renderTargetPriv().attachStencilAttachment(stencil)) {
             if (newStencil) {
                 // Right now we're clearing the stencil attachment here after it is
-                // attached to a RT for the first time. When we start matching
+                // attached to an RT for the first time. When we start matching
                 // stencil buffers with smaller color targets this will no longer
                 // be correct because it won't be guaranteed to clear the entire
                 // sb.