* Push/pop the variable scope stack when validating blocks
* Handle nested blocks in ValidateStatement()
* Add test coverage
This also fixes issues with other types of validation errors not being
caught when inside nested blocks.
Change-Id: Ia8d0138b346a8a7aa607497d51fd6aaf675dc8be
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39980
Auto-Submit: James Price <jrprice@google.com>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>