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

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

7030606: Project-coin: multi-catch types should be pairwise disjoint
Summary: Bring javac in sync with latest Project Coin EDR
Reviewed-by: jjg