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 41405c04.

Revert "X87: Revert of Revert of [strong] Implement strong mode restrictions on property access."

This reverts commit 48de5f4d.

Revert "Fix overlapping KeyedLoadIC bitfield."

This reverts commit 4e6c956a.

Revert "MIPS64: Fix 'Revert of Revert of [strong] Implement strong mode restrictions on property access'."

This reverts commit 74f97b0d.

BUG=

Review URL: https://codereview.chromium.org/1199493002

Cr-Commit-Position: refs/heads/master@{#29166}