Even though SO may not be correct
overrides sometimes, it feels more
natural to treat fake overrides as...
well, "overrides". And without it
we'd need to make the code in
`FirOverrideChecker` less intuitive.
Properly set up dom-api-compat dependency for JS IR tests. Since this dependency is added
automatically for every Kotlin/JS library, it should be present during tests just as stdlib.
As a result, tests for serializable enums were changed since 1.6.0 runtime does not require enums to be explicitly serializable.