The implicit assignment to the induction variable in a ForInStatement
has been ignored by the AST loop assignment analysis. This was hidden
for cases where the parser introduced a ".for" temporary, but triggers
when the variable is declared outside the loop.

R=bmeurer@chromium.org
TEST=mjsunit/regress/regress-crbug-647887
BUG=chromium:647887

Review-Url: https://codereview.chromium.org/2356733002
Cr-Commit-Position: refs/heads/master@{#39551}