[layoutng] Re-set the fragment after getting the cloned cached fragment

See the comments in the patch for why this is necessary.

R=eae@chromium.org, ikilpatrick@chromium.org

Bug: 635619
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I0a4042c0782c98fab1bfd27cb3bf6ca29c820542
Reviewed-on: https://chromium-review.googlesource.com/1013306
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551237}
1 file changed