Update filepath of blink_test_runner watchlist.

DumpRenderTree is long gone and has been replaced by content_shell.

https://groups.google.com/a/chromium.org/d/topic/blink-dev/e8rhoAZcfSU/discussion

BUG=None
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Review URL: https://codereview.chromium.org/1383983004

Cr-Commit-Position: refs/heads/master@{#353805}
1 file changed