This is a workaround for the problem KT-43321.
Introduce an intermediate abstract set specialized for Map.Entry elements
and implement 'contains(Map.Entry)' method there.
Then inherit that intermediate set in entrysets of JS HashMap,
JS LinkedHashMap, JVM MapBuilder, that are specialized for
MutableMap.MutableEntry elements, so that no override of 'contains' is
required anymore.
This allows to avoid incorrect special 'contains' bridge being generated
that otherwise rejects all arguments except ones of MutableEntry type.
Ilya Gorbunov
28168bf230