Adds support for strict mode load / store ICs and cleans up BinaryOp and
CompareOp to only trigger an UNIMPLEMENTED abort if called with STRONG
mode (which is the only language mode which has different compare/binary ops.

BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1385623002

Cr-Commit-Position: refs/heads/master@{#31134}