Using a global proxy (e.g. 'window.f', 'w.f' or 'this.f') is considerably slower than evaluating just 'f'. This CL aims to perform the necessary checks at compile time and inline the accesses.

This is a follow-on CL to crrev.com/2369933005:
- The initial upload is crrev.com/2369933005 + a rebase.
- The remaining issues are the fixes requested by the reviewers on that CL.

BUG=chromium:634276

Review-Url: https://codereview.chromium.org/2403003002
Cr-Commit-Position: refs/heads/master@{#40153}