Go code intelligence: jump to def in standard library references do not work

Created by: christinaforney

Steps to reproduce:

1. Go to a file with defer statements: https://sourcegraph.com/github.com/sourcegraph/sourcegraph@23f28cdb6e3b34488e81411ae5014164f144f480/-/blob/cmd/repo-updater/repos/testing.go#L520:13
2. Hover over line 520 (or any other defer statement): defer a.mu.Unlock()
3. Expect Unlock() to show a hover, but it does not.

All other standard library references do not have a hover jump to def response.

This is happening for both the chrome extension and sourcegraph.com