This moves bits that are accessed during a stack-walk out if the first
kind-specific flags field. Such bits are accessed during evacuation
within the GC and hence need to remain directly in the {Code} object,
the other bits in the kind-specific flags are mutable and hence will be
moved into a separate data container object.

R=jarin@chromium.org
BUG=v8:6792

Change-Id: I20b7d307110ca0c0eb6dd4df31a35fab4701c6da
Reviewed-on: https://chromium-review.googlesource.com/735145Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48877}