Load WasExperimental values correctly for associated declarations

For example, if a class is `@SinceKotlin("X")
@WasExperimental(M::class)`, then its constructor should also be
accessible if API < X, provided that the opt-in to M is given

compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/classesAndConstructors.kt

@@ -8,6 +8,8 @@ class Bar @SinceKotlin("1.1") constructor()
 @SinceKotlin("1.0")
 class Baz @SinceKotlin("1.1") constructor()
 
+@SinceKotlin("1.1")
+class Quux @SinceKotlin("1.0") constructor()
 
 fun t1(): <!API_NOT_AVAILABLE!>Foo<!> = <!UNRESOLVED_REFERENCE!>Foo<!>()
 
@@ -17,3 +19,5 @@ fun t2() = object : <!UNRESOLVED_REFERENCE, API_NOT_AVAILABLE, API_NOT_AVAILABLE
 fun t3(): Bar? = <!UNRESOLVED_REFERENCE!>Bar<!>()
 
 fun t4(): Baz = <!UNRESOLVED_REFERENCE!>Baz<!>()
+
+fun t5(): <!API_NOT_AVAILABLE!>Quux<!> = <!UNRESOLVED_REFERENCE!>Quux<!>()