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

8062348: langtools tests should close file manager (group 1)
Reviewed-by: darcy

7124605: typos in javac comments
Reviewed-by: ksrini

7086601: Error message bug: cause for method mismatch is 'null'
Summary: Inference error during lub() does not set 'cause' for method resolution diagnostic
Reviewed-by: jjg