The following interface blocks should fail link:

    VS:
    layout(binding=0) buffer BufferBlockNameA
    {
        mediump float variable;
    };

    FS:
    layout(binding=1) buffer BufferBlockNameB
    {
        mediump float variable;
    };

Because `variable` is ambiguous.

Bug: angleproject:3580
Change-Id: I29576a6f152780819af0e9fb63249dbee7d9f2fc
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2587450Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>