Several users of kKindSpecificFlags1Offset (aliased as kFullCodeFlags) were
reading/writing bytes -- not endian agnostic.

TEST=mjsunit/debug-setexceptionbreak, mjsunit/debug-mirror-cache, mjsunit/regress/regress-94873, others...
BUG=

Review URL: https://codereview.chromium.org/1236143002

Cr-Commit-Position: refs/heads/master@{#29634}