Truffle/Instrumentation: remove the abstract method TruffleLanguage.getDefaultASTProber() around issues of timing in the Engine and language startup sequences. TruffleLanguage implementations requiring any Instrumentation services are now required to register (at least) the languages "default" ASTProber for configuring tool behavior; this must be done before any RootNotes are created.

Please see http://openjdk.java.net/contribute/ for details of how to contribute
to OpenJDK projects including GraalVM.