MIPS: Fix `[proxies] fix access issue when having proxies on the prototype-chain of global objects.`

Port 2c75e3d2

Original commit message:
We can no longer just walk the prototype chain without doing proper access-checks. When installing a proxy as the __proto__ of the global object we might accidentally end up invoking cross-realm code without access-checks (see proxies-cross-realm-ecxeption.js).

BUG=

Review URL: https://codereview.chromium.org/1526253006

Cr-Commit-Position: refs/heads/master@{#32921}