RFR (T) 8221992: Fix old method replacement in ResolvedMethodTable

[coleen.phillimore at oracle.com]

Summary: Use method get_new_method() which is used in other call sites.

See bug for more details.  Ran hs-tier1-3 and redefinition tests 
locally, including the one added for this code:
test/jdk/java/lang/instrument/RedefineAddDeleteMethod/MethodHandleDeletedMethod.java

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8221992.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8221992

Thanks,
Coleen