8129962: Investigate performance improvements in langtools combo tests
Summary: New combo API that runs all combo instances in a shared javac context (whenever possible).
Reviewed-by: jjg, jlahoda, vromero

8076543: Add @modules as needed to the langtools tests
Reviewed-by: jjg, shurailine

8006694: temporarily workaround combo tests are causing time out in several platforms
Reviewed-by: jjg
Contributed-by: maurizio.cimadamore@oracle.com

8005852: Treatment of '_' as identifier
Summary: warn when '_' is found in an identifier position
Reviewed-by: jjg

8005167: execution time of combo tests in javac should be improved
Reviewed-by: jjg, jjh

8002099: Add support for intersection types in cast expression
Summary: Add parser and type-checking support for intersection types in cast expressions
Reviewed-by: jjg

8003280: Add lambda tests
Summary: Turn on lambda expression, method reference and default method support
Reviewed-by: jjg

7124605: typos in javac comments
Reviewed-by: ksrini

7115050: Add parser support for lambda expressions
Summary: Add support for parsing lambda expressions to JavacParser
Reviewed-by: jjg