JS frontend: additional check for nativeSetter -- check that the return type is either Unit or a supertype of the second parameter's type.

compiler/testData/diagnostics/testsWithJsStdLib/native/nativeSetter/onToplevelExtensionFun.kt

@@ -4,12 +4,21 @@ nativeSetter
 fun Int.set(a: String, v: Int) {}
 
 nativeSetter
-fun Int.set2(a: Number, v: String?) = "OK"
+fun Int.set2(a: Number, v: String?): Any? = null
 
 nativeSetter
-fun Int.set3(a: Double, v: String?) = "OK"
+fun Int.set3(a: Double, v: String) = "OK"
 
-[nativeSetter]
+nativeSetter
+fun Int.set4(a: Double, v: String): Any = 1
+
+nativeSetter
+fun Int.set5(a: Double, v: String): CharSequence = "OK"
+
+nativeSetter
+fun Int.set6(a: Double, v: String): <!NATIVE_SETTER_WRONG_RETURN_TYPE!>Number<!> = 1
+
+nativeSetter
 fun Any.foo(<!NATIVE_INDEXER_CAN_NOT_HAVE_DEFAULT_ARGUMENTS!>a: String = "0.0"<!>, <!NATIVE_INDEXER_CAN_NOT_HAVE_DEFAULT_ARGUMENTS!>v: String = "str"<!>) = "OK"
 
 <!NATIVE_INDEXER_WRONG_PARAMETER_COUNT!>nativeSetter