RFR(S): 8230915: [lworld] Deoptimization fails with assert(value->type() == T_OBJECT) failed: object element expected

[Roland Westrelin]

http://cr.openjdk.java.net/~roland/8230915/webrev.00/

This includes a backport of 8231055 because it tweaks the same
code. When a copy is made with same source and destination, the existing
code would compute adr_type using the offset of the source, ignoring
source and destination positions. The adr_type needs to either use the
offset with src and dest positions factored in (if they are constant) or
the source offset to determine the field offset in a flattened array
with an unknown element index.

Roland.