RFR 9: JDK-8144552 : java/lang/StackWalker/LocalsAndOperands.java fails with java.lang.NullPointerException

[Brent Christian]

Hi,

Please review my change for

8144552 : java/lang/StackWalker/LocalsAndOperands.java fails with 
java.lang.NullPointerException

Bug:
https://bugs.openjdk.java.net/browse/JDK-8144552
Webrev:
http://cr.openjdk.java.net/~bchristi/8144552/webrev.0/

It's possible for the LiveStackFrame.getLocals() array to contain null 
entries, in particular in the case of "dead" local variables.

The (package-private) docs are being updated to state this.  The test 
case is updated to keep the locals in the test() method alive (and 
checked for non-null), and otherwise be tolerant of nulls.

Thanks,
-Brent