Instead of limiting the number of used spill slots and bailing out if
the limit is exceeded, we now store the number of spill slots used and
patch the stack frame size after generating all code.
This removes a lot of checks and bailouts.

Drive-by: Fix a bug with spilling f64 caller frame slots which was
uncovered by the additional test coverage after this CL.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: I25d856f99451642cc15239c0461402e51487d0a1
Reviewed-on: https://chromium-review.googlesource.com/929162Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51500}