This fixes source position tracking within the "increment" expression of
a for-statement. The old {StashCode} method was inherently incompatible
with side tables like the source position table, as it would leave them
untouched while mutating the bytecode stream. It was hence trimmed down
to {DeleteCode}.

R=bradnelson@chromium.org
BUG=v8:6127

Change-Id: I7a5ff60cd5334208c44b165c8b54144d9ae83209
Reviewed-on: https://chromium-review.googlesource.com/480301
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44714}