Add a release assert in Element's constructor to track down a crasher
Add a release assert in Element's constructor to track down a crasher

R=abarth@chromium.org
BUG=312410

Review URL: https://codereview.chromium.org/102993010

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@164442 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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