This reverts commits
* 45c11887 "[fullcodegen] Remove dead hole check logic"
* 2aaf217b "[crankshaft] Remove dead Variable hole-checking code"
* f40a3817 "[crankshaft] Fix mips/mips64 build: remove unused variable"

BUG=
R=adamk@chromium.org,bmeurer@chromium.org,hablich@chromium.org

Review-Url: https://codereview.chromium.org/2640793004
Cr-Commit-Position: refs/heads/master@{#42476}