RFR (XS): 8027632: assert(xtype->klass_is_exact()) failed: Should be exact at graphKit.cpp

[Roland Westrelin]

http://cr.openjdk.java.net/~roland/8027632/webrev.00/

When doing profile collection for receiver type at an invokevirtual/invokeinterface, c1 uses the holder of a method as the known class if a single type is known to be possible. For default methods, the holder of the method may be an interface and the profile collection is wrong. 

The bug triggered an assert in type speculation but it’s actually unrelated to type speculation.

Roland.