DevTools: page.navigate should fail when server returned HTTP 204

Browser doesn't commit navigation if server responds HTTP 204 / HTTP 205
for the main resource or if navigation triggers a download.

In these cases, navigation is considered aborted.

This patch teaches page.navigate to return "ERR:ABORTED" when
either of the usecases happens.

R=dgozman, pfeldman

Change-Id: I0017e458c2f905429c7234bc8f9be20a4201bbfd
Reviewed-on: https://chromium-review.googlesource.com/1009487
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Camille Lamy <clamy@chromium.org>
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551261}
5 files changed