* Add support for class private methods
This commit adds parser support for the TC39 Stage 2 Private Methods
proposal.
This commit also changes "key" in ClassPrivateProperty from an
Identifier to a PrivateName, as well as disallowing #constructor as a
valid private field name.
* Add tests for string literal get/set/async
These should be treated as regular methods and not special get/set/async
behaviour.
* Add tests for class private methods
This also removes a test from the Test262 whitelist that failed before
the changes for private methods support and now passes.
* Modify class private prop tests for PrivateName
* Add class private prop tests for #constructor
* Fix existing ASI test case failure
* Integrate Test262
Introduce a GNU Make target for retrieving TC-39's Test262 suite and
validating parsing of the files it contains. Interpret each file as a
parser test in accordance with that project's `INTERPRETING.md`
document. Allow for the specification of allowed failures via a
"whitelist" file so that the test suite may help prevent regressions in
this project in situations where this project has known bugs. Initialize
the "whitelist" file with a listing of all tests that are currently
failing. Extend the continuous integration environment's configuration
to automatically run these tests.
* use graceful-fs and latest yarn on travis
