Review Request for 8025799: Restore sun.reflect.Reflection.getCallerClass(int)

[Mandy Chung]

JDK 8 was feature complete in June and there just isn't sufficient time 
remaining to get agreement and feedback on an API to examine the caller 
frames. To that end, I propose to restore the old unsupported 
Reflection.getCallerClass(int) and that we will look to define a 
standard API for JDK 9.

Webrev at:
   http://cr.openjdk.java.net/~mchung/jdk8/webrevs/8025799/

It remains to be an unsupported API and JDK should not use this method 
and it's not annotated with @CallerSensitive.  I considered detecting if 
this method is called by a system class (loaded by null loader) and 
throw an error.  I decided to minimize the compatibility risk in case if 
there is any existing code added to the bootclasspath depending on this 
private API.

Thanks
Mandy