Removes assignment hazard scope. Reverts back to the naive scheme of
allocating a temporary for every variable load. It was decided to revert it
because the current implementation does not handle logical expressions,
ternary operators, visiting objects in named/keyed loads. Also, we wanted
to evaluate alternate approaches and choose one when we have a mechanism
to measure performance.

BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1576403004

Cr-Commit-Position: refs/heads/master@{#33269}