[lworld] RFR(S): 8220583: [lworld] Missing ValueTypeNode for value type receiver

[Tobias Hartmann]

Hi,

please review the following patch:
https://bugs.openjdk.java.net/browse/JDK-8220583
http://cr.openjdk.java.net/~thartmann/8220583/webrev.00/

GraphKit::set_arguments_for_java_call() sometimes sees unexpected oops for a value type receiver. We
should scalarize after a value type receiver null check.

The change also contains some refactoring and a small optimization when loading from a static,
initialized value type field.

Thanks,
Tobias