Merge to M58: Resolve preloadResponse of Navigation Preload even if the response body is empty.

Merge to M58: Resolve preloadResponse of Navigation Preload even if the response body is empty.

BUG=706765, 691503
TEST=virtual/service-worker-navigation-preload-wpt/external/wpt/service-workers/service-worker/navigation-preload/empty-preload-response-body.https.html

Review-Url: https://codereview.chromium.org/2787783002
Cr-Commit-Position: refs/heads/master@{#461082}
(cherry picked from commit f37399e1cb91a70730938f61008142ce61a00ad6)

Review-Url: https://codereview.chromium.org/2791963002 .
Cr-Commit-Position: refs/branch-heads/3029@{#540}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed: https://chromium.googlesource.com/chromium/src/+/432269484584455b81b68bb58d0a356c0da29456

[horo, 2017-04-03 08:12:16]

Description was changed from

==========
Merge to M58: Resolve preloadResponse of Navigation Preload even if the response
body is empty.

BUG=706765,691503
TEST=virtual/service-worker-navigation-preload-wpt/external/wpt/service-workers/service-worker/navigation-preload/empty-preload-response-body.https.html

Review-Url: https://codereview.chromium.org/2787783002
Cr-Commit-Position: refs/heads/master@{#461082}
(cherry picked from commit f37399e1cb91a70730938f61008142ce61a00ad6)
==========

to

==========
Merge to M58: Resolve preloadResponse of Navigation Preload even if the response
body is empty.

BUG=706765,691503
TEST=virtual/service-worker-navigation-preload-wpt/external/wpt/service-workers/service-worker/navigation-preload/empty-preload-response-body.https.html

Review-Url: https://codereview.chromium.org/2787783002
Cr-Commit-Position: refs/heads/master@{#461082}
(cherry picked from commit f37399e1cb91a70730938f61008142ce61a00ad6)

Review-Url: https://codereview.chromium.org/2791963002 .
Cr-Commit-Position: refs/branch-heads/3029@{#540}
Cr-Branched-From:
939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed:
https://chromium.googlesource.com/chromium/src/+/432269484584455b81b68bb58d0a...
==========

[horo, 2017-04-03 08:12:19]

Committed patchset #1 (id:1) manually as
432269484584455b81b68bb58d0a356c0da29456.