Quickfix for NOTHING_TO_OVERRIDE: change function signature to match one of super function's signatures.

This implements "Modify method parameters/return type to match one of method in super-classes." solution from https://docs.google.com/document/d/1b9I-7VUMq8As9gd4agU8hPIXrBauplG8_4vLK5Pv-zw/edit#heading=h.6g59oaej69hc

This pull-request (hopefully) fixes issues mentioned in https://github.com/JetBrains/kotlin/pull/232.