RFR: 8193930: [JVMCI] calling ResolvedTypeType.getClassInitializer on an array type crashes

[Doug Simon]

Please review this simple fix for a VM crash when calling ResolvedTypeType.getClassInitializer on an array type.

In addition to fixing the code for ResolvedTypeType.getClassInitializer, this patch also makes CompilerToVM.getImplementor more robust in case it is called with a ResolvedjavaType representing a non-interface type.

Lastly, there are a few minor comment formatting changes that were made automatically by Eclipse. I'd like to keep them as Eclipse is the preferred tool for developing JVMCI code.

https://bugs.openjdk.java.net/browse/JDK-8193930
http://cr.openjdk.java.net/~dnsimon/8193930/

-Doug