Use string literal style for shader string in WebGLCompatibilityTest Bug: None Change-Id: I75255cfda3793c539ac8a6ee2c50b8526bfc9286 Reviewed-on: https://chromium-review.googlesource.com/c/1493113 Commit-Queue: Shrek Shao <shrekshao@google.com> Reviewed-by: Jamie Madill <jmadill@google.com>