Fixed issue where findAllRefs on identifiers starting with 2+ underscores failed.
Added to comment.
Don't explicitly make diagnostics in the parser.
Don't report a diagnostic explicitly.
Merge pull request #1240 from Microsoft/underscoreTS

Fix for findAllRefs on identifiers starting with 2+ underscores
Merge pull request #1251 from Microsoft/reduceDiagnostics

Reduce diagnostics
Merge remote-tracking branch 'ts_official/master'