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This moves the new isolated-script-based installer test to run on
Win10 as an experiment, rather than running locally on Win Fast
Ring (also fixing the gtest misconfiguration).

No-Try: true
Bug: 827546

Change-Id: I687a763d81c7095c88a6c879156ff2043336a863
Reviewed-on: https://chromium-review.googlesource.com/988260Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547843}