7192246: Add type-checking support for default methods
Summary: Add type-checking support for default methods as per Featherweight-Defender document
Reviewed-by: jjg, dlsmith
Neg07.java:16:12: compiler.err.override.incompatible.ret: (compiler.misc.cant.implement: m(), Neg07.C1, m(), Neg07.I), void, int
Neg07.java:19:21: compiler.err.override.incompatible.ret: (compiler.misc.cant.implement: m(), Neg07.C3, m(), Neg07.I), void, int
2 errors