test: Fix 956-methodhandle-stackframe for javac/dx

javac apparently doesn't like to use #invoke and #invokeExact through a
MethodHandle subclass.

This seems allowed by JLS so perhaps it might be a javac bug?

Bug: 36902714
Test: art/test/run-test  --host --build-with-javac-dx 958-methodhandle-stackframe
Change-Id: I6c3559502a6a84b4bc2ad884bbbd9d942c5bca94
2 files changed