8157957: ClassNotFoundException: jdk.test.lib.JDKToolFinder
Reviewed-by: coleenp, gtriantafill, mseledtsov, iignatyev, dholmes, dsamersoff

8072588: JVM crashes in JNI if toString is declared as an interface method
Summary: Check for a valid itable index instead of checking if the holder is an interface
Reviewed-by: dsimms, dholmes