OverridingUtil will be present at runtime and we should strive to minimize the
size of our runtime classes
Also add a comment to getOverriddenDescriptors()
Fix warnings, simplify code. Untangle a very complex code related to
diagnostics on multiple default values and different names of parameters in
supertypes; fix a bug there, add test
The intent was to keep the bridge codegen model as simple as possible: we
should be able to figure out all necessary bridges only by a minimal interface
that FunctionHandle provides (isAbstract, isDeclaration, getOverridden)
Add different tests for bridges
#KT-318 Obsolete