When executing register moves, we might need to spill registers to the
stack. Ensure that we don't exceed the reserved stack space for the
current frame.

R=ahaas@chromium.org

Bug: v8:7366, v8:6600
Change-Id: Ic11ff2ff5f46535c3663ef4cf62b095f6c8ba637
Reviewed-on: https://chromium-review.googlesource.com/883282
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50847}