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

This reverts r164442.

The RELEASE_ASSERT never fired in production, so we might as well remove it.

R=abarth@chromium.org
BUG=312410

Review URL: https://codereview.chromium.org/145263006

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@165779 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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