Make no-location redirect response to be "opaque redirect" when redirect mode is manual.

According to the spec, even if location header is not set, we should
treat the redirect response as "opaqueredirect" if the redirect mode
of the fetch request is "manual".

This behavior was changed by this commit on the spec.
https://github.com/whatwg/fetch/commit/3e501f29eceff41eb81c60fb9937e33e23cf5492

BUG=707185

Review-Url: https://codereview.chromium.org/2785123002
Cr-Commit-Position: refs/heads/master@{#464329}
8 files changed