review request (M): 7032850: MethodHandle.invokeGeneric throws unspecified RuntimeException if parameterized method is called

[John Rose]

http://cr.openjdk.java.net/~jrose/7032850/webrev.00/

7032850: MethodHandle.invokeGeneric throws unspecified RuntimeException if parameterized method is called
Summary: Implement invocation corner cases, including correct type conversions and interface type enforcement.

This is a fix for invoke[Generic], which was failing to process some reference conversions correctly.

This includes a related fix for interface conversions; the code was not issuing checkcasts against interfaces for asType adapters.

-- John