Review request for JDK-8010652

[Attila Szegedi]

Please review JDK-8010652 "Eliminate non-child references in Block/FunctionNode, and make few node types immutable" 

Unified patch:
<http://cr.openjdk.java.net/~attila/8010652/webrev.00/>

For ease of comprehension I'm also providing 8 incremental patches containing changes broken out into semantic units:
<http://cr.openjdk.java.net/~attila/8010652/webrev.00/incrementalPatches>