[layoutng] Correctly set the exclusion space when cloning

Due to variable shadowing the exclusion space was always null after
cloning, causing problems with fragment caching.

R=eae@chromium.org
BUG=635619

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I5aca88fdc693f1ad64848f43a108953bf1fc8f65
Reviewed-on: https://chromium-review.googlesource.com/986992
Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547045}
1 file changed