RFR: 8230851 Interpreter could avoid calling the runtime for defaultvalue

[Frederic Parain]

Please this review this small change in the interpreter adding
a fast path to defaultvalue.

CR: https://bugs.openjdk.java.net/browse/JDK-8230851
Webrev: http://cr.openjdk.java.net/~fparain/opt_int/webrev.00/index.html

Thank you,

Fred