JDK-8217998: Remove method_type field associated with the appendix field of an indy or method handle call

[Lois Foltan]

Please review this change that removes the unused method_type field 
associated with the appendix field of an indy or method handle call.  
This is the first of a series of changes working towards JDK-8210685: 
Bootstrap method consolidation.

open webrev at: http://cr.openjdk.java.net/~lfoltan/bug_jdk8217998.1/webrev/
bug link: https://bugs.openjdk.java.net/browse/JDK-8217998
co-contributors: Lois Foltan & John Rose

Testing: hs-tier1-4 & jdk-tier1-3 (all platforms), hs-tier5-8 (linux 
only), JCK vm & lang (linux only)

Thanks,
Lois