Request for review (S) 4926272: methodOopDesc::method_from_bcp is unsafe

[Coleen Phillimore]

Summary: Instead of using GC to find the block start, scan backward in 
memory to known contents in the constMethodOop

open webrev at http://cr.openjdk.java.net/~coleenp/4926272/
bug link at http://bugs.sun.com/view_bug.do?bug_id=4926272

Tested on 32 and 64 bit platforms with the test cases that reliably failed.

Thanks,
Coleen