Enable loads and stores to global vars through property cell shortcuts installed into parent script context.
Enable loads and stores to global vars through property cell shortcuts installed into parent script context.

Review URL: https://codereview.chromium.org/1330213003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#30684}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh