fix(UTs): Correct proxy listeners expectation
fix(UTs): Correct proxy listeners expectation

Expectations added in https://github.com/karma-runner/karma/pull/2596
didn't match `EventEmitter` API for `listeners`.

johnjbarton/karma,maksimr/karma,karma-runner/karma,johnjbarton/karma,david-garcia-nete/karma,karma-runner/karma,david-garcia-nete/karma,david-garcia-nete/karma,karma-runner/karma,maksimr/karma,johnjbarton/karma,karma-runner/karma,johnjbarton/karma,maksimr/karma