Reason:
Regressions in various benchmarks.
Revert "Revert of Revert of [strong] Implement strong mode restrictions on property access (patchset #1 id:1 of https://codereview.chromium.org/1189153002/)"
This reverts commit 41405c0470.
Revert "X87: Revert of Revert of [strong] Implement strong mode restrictions on property access."
This reverts commit 48de5f4d6b.
Revert "Fix overlapping KeyedLoadIC bitfield."
This reverts commit 4e6c956abf.
Revert "MIPS64: Fix 'Revert of Revert of [strong] Implement strong mode restrictions on property access'."
This reverts commit 74f97b0d2a.
BUG=
Review URL: https://codereview.chromium.org/1199493002
Cr-Commit-Position: refs/heads/master@{#29166}