Improve and update test262 integration

1. Update the test262 submodule to the latest version

This brings more test cases to already enabled folders, but also
requires more exclusions of currently failing checks.

2. Improve test262 runner (Test262SuiteTest class)

* Allow arbitrary names of expected exceptions and support the new
  structure of the 'negative' section in tests' metadata
* Distinguish exception's phase, early vs runtime, for negative tests
* Support for a 'raw' flag: no harness files, implies 'noStrict'
* Add filtering by the 'features' lists
* Exclude tests with a 'module' flag, as this isn't supported by Rhino
* Exclude tests with an 'async' flag, which isn't yet supported by
  the Test262SuiteTest itself
* Couple of other smaller fixes

3. Enable more tests, mostly from the 'language' folder

This brings the total number of passing tests to 44k.