It is invalid for OSR deconstruction to leave a graph with a node
representing the OSR normal entry (and no OSR loop entry). Subsequent
lowering phases will not handle {OsrNormalEntry} operators and hence
will lead to serious clogging further down the pipeline.

R=bmeurer@chromium.org
BUG=chromium:641893

Review-Url: https://codereview.chromium.org/2336543002
Cr-Commit-Position: refs/heads/master@{#39340}