- Implement new WebAssembly.LinkError exception
- Implement stricter checks for glboal imports
- Add tests
- Refactor handling of import names
- Add TODOs for empty import names

R=titzer@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2584843002
Cr-Commit-Position: refs/heads/master@{#41764}