Code review request: 7086586 Inference producing null type argument

[Dmeetry Degrave]

hi,

i'm looking for a code review for 7086586 fix for 7u4. It implements fix 
suggested by Maurizio for problem 2 from evaluation.

bug description: http://bugs.sun.com/view_bug.do?bug_id=7086586
jdk7 evaluation: http://bugs.sun.com/view_bug.do?bug_id=2213800

webrev: http://cr.openjdk.java.net/~dmeetry/7086586/webrev.00/

thanks,
dmeetry