RFR 8231146: Heap object size

[Roger Riggs]

Please review and comment:

This request adds a (probably temporary) API to return the heap size of 
an object.

In prototyping with inline classes it will be useful to know an 
approximation of the size of an object in the heap while prototyping 
various tradoffs in performance and data structures.


Webrev:

   http://cr.openjdk.java.net/~rriggs/webrev-object-size-8231146/

Thanks, Roger