GLES: Expose OES_mapbuffer in GLES2 on GLES3.

This extension is mandatory for EXT_map_buffer_range support. We can
emulate it using GLES 3.0 core map functionality.

BUG=angleproject:1751

Change-Id: Idba09ce7276603d5556039f4a49aa0b87cae22aa
Reviewed-on: https://chromium-review.googlesource.com/431826
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/validationES.cpp b/src/libANGLE/validationES.cpp
index 3d9dba3..3607de6 100644
--- a/src/libANGLE/validationES.cpp
+++ b/src/libANGLE/validationES.cpp
@@ -1230,7 +1230,7 @@
             if (!extensions.mapBuffer)
             {
                 context->handleError(
-                    Error(GL_INVALID_ENUM, "pname requires OpenGL ES 3.0 or GL_OES_map_buffer."));
+                    Error(GL_INVALID_ENUM, "pname requires OpenGL ES 3.0 or GL_OES_mapbuffer."));
                 return false;
             }
             break;
@@ -1242,7 +1242,7 @@
             {
                 context->handleError(Error(
                     GL_INVALID_ENUM,
-                    "pname requires OpenGL ES 3.0, GL_OES_map_buffer or GL_EXT_map_buffer_range."));
+                    "pname requires OpenGL ES 3.0, GL_OES_mapbuffer or GL_EXT_map_buffer_range."));
                 return false;
             }
             break;
@@ -4366,7 +4366,7 @@
     {
         context->handleError(
             Error(GL_INVALID_OPERATION,
-                  "Context does not support OpenGL ES 3.0 or GL_OES_map_buffer is not enabled."));
+                  "Context does not support OpenGL ES 3.0 or GL_OES_mapbuffer is not enabled."));
         return false;
     }