[Fetch] Response.clone should tee the body stream.

[Fetch] Response.clone() should tee the body stream.

Previously Response.clone() does not refresh the body property
and hence was not able to read data from the original response.

This CL fixes the problem.

BUG=435393
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192923

[yhirano, 2015-04-01 02:55:57]

yhirano@chromium.org changed reviewers:
+ horo@chromium.org

[horo, 2015-04-01 04:12:35]

lgtm

[yhirano, 2015-04-01 04:13:02]

The CQ bit was checked by yhirano@chromium.org

[commit-bot: I haz the power, 2015-04-01 04:13:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1053503002/60001

[commit-bot: I haz the power, 2015-04-01 10:08:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-01 10:08:08]

Try jobs failed on following builders:
  mac_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/49915)

[yhirano, 2015-04-01 10:08:35]

The CQ bit was checked by yhirano@chromium.org

[commit-bot: I haz the power, 2015-04-01 10:09:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1053503002/60001

[commit-bot: I haz the power, 2015-04-01 11:29:07]

Committed patchset #4 (id:60001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192923