* migrate nullish coalescing commit
* add more test case
* add branch type check test
* add more tests
* fix nullish precedence
* update public api
* add rescan question question token to fix regression
* update public api baseline
* Added tests that emit for nullish coalescing operator conforming with grammar restrictions when assertions are used.
* Fixed emit to hoist temporary variables (they previously went undeclared).
Added tests to ensure calls and property accesses are only called once.
* use not equal to null
* rename factory
* add grammar check
* fix more cases
* Fix handling of nullish coalescing oprator in expando objects.
* Fixed classifier to support ?? operator.
* update baseline
* accept baseline
* fix review
* update emitter and more testcase
* update control flow
* make linter happy
* update libs
* avoid unnecessary assert
* fix typooo
* Fixes for control-flow analysis