Enable to call default method on java8

[tuchida]

When call Predicate#negate (default method) in java8.
https://docs.oracle.com/javase/8/docs/api/java/util/function/Predicate.html#negate--

var p = java.util.function.Predicate({
  test: function(t) {
    return true;
  }
}).negate();
p; // null

By right, the method return Predicate's instance, but returned null.
The negate method is generated from JavaAdapter in Rhino, and that body is empty.

So I made this:

• Do not generate default method in JavaAdapter.
• Add default method to JavaMember.

[gbrail]

Thanks -- I get this, and I think that's a good way to handle it.

However, I'd like to publish 1.7.6 soon, and I think that changing the build process so that 1.8 is required to build it is a bit of a big deal -- I'd rather push that out until 1.8.0. (I'd also like to change the build process so that we can use InvokeDynamic optionally at runtime, so that's a good time to do that as well.)

[tuchida]

Thanks.

we can use InvokeDynamic optionally at runtime

Sounds good!

[eshepelyuk]

@gbrail could you share usage scenarios for InvokeDynamic ?

[gbrail]

I merged this in a different PR -- things have changed but it's still valid. Take a look at #340.

[gbrail]

Fixed this in #343.