RFR: JDK-8209604: [TEST] rewrite com/sun/jdi shell tests to java version - step2

[Alex Menkov]

Hi all,

Please review next chunk of shell->java test conversion.
jira: https://bugs.openjdk.java.net/browse/JDK-8209604
webrev: http://cr.openjdk.java.net/~amenkov/sh2java/step2/webrev/

The fix contains some changes in library classes:
Jdb.java - timeouts are updated (as per Dan note in one of previous 
review, timeouts should respect timeout factor, Utils.adjustTimeout 
implements the functionality);
JdbCommand.java - new jdb commands (required by tests) are added.

--alex