Fix bug in request-init-003.sub.html

According to the Fetch spec, the Request constructor is called
with |input| only, then referrer attribute will be set to
"about:client".

From fetch spec, https://fetch.spec.whatwg.org/#concept-request:
Unless the referrer is set to anther value in request, it is set to
"about:client" by default.

BUG=624278

Review-Url: https://codereview.chromium.org/2802153002
Cr-Commit-Position: refs/heads/master@{#462811}
2 files changed