This extends the matching of arithmetic operations against the loop
induction variable to speculative number operations (on top of the
existing JS-level operations). This is needed now that lowering to
speculative operations is done during graph construction.

R=jarin@chromium.org
BUG=chromium:693035

Change-Id: I7c3f71af92b5c059f1d7b3b7f2d3b4a73d7dc43d
Reviewed-on: https://chromium-review.googlesource.com/445196Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43325}