[jumbo] Two blink tests used kViewportWidth in a way that clashed

This moves two kViewportWidth and two kViewportHeight into
tighter scopes to reduce risk for future clashes in jumbo builds.

Change-Id: I7527018809a4bf62b8e831e18235327b11a95f29
Reviewed-on: https://chromium-review.googlesource.com/c/1386149
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#618168}
2 files changed