Do not import WPT WebDriver tests that have spaces

Test names with spaces are causing syntax errors in expectation files.

TBR to unblock wpt-importer; no-try because this file is only used by
the importer.

TBR=foolip

No-Try: True
Bug: 974254
Change-Id: Ia15bf96f59fe5fdaa97828ff4bf464b578e90c20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660355
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669259}