Previously, this check was done with bracket property access on the
global object: global['goog']
This will not be minified when Closure compiles this code, which:
1) breaks, because 'goog' will have been minified but the check won't have
taken that into consideration
2) causes build failures in g3, because the actual property 'goog' is
forbidden in some published JS code (to ensure obfuscation).
A TODO is added to validate that this logic is correct, as it's difficult to
test within the Angular repo.
PR Close#29873
f6ee1c2219