Request for reviews (S): 6820514: meet not symmetric failure in ctw

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6820514/webrev.01

Fixed 6820514: meet not symmetric failure in ctw

Problem:
Missing instance_id meet for the case j.l.Object:NotNull
meets unloaded instance klass.

Solution:
Add instance_id meet in TypeInstPtr::xmeet_unloaded().
Fix Type::interface_vs_oop() for narrow oops (cases
regression test 6837094 failure).
Remove optional instance_id in TypeOopPtr::make()
as I promised before.

Reviewed by:

Fix verified (y/n): y, ctw test from bug and 6837094 test

Other testing:
JPRT