JS: more default arguments fixes (KT-24413, KT-21968 fixed)

MPP-related:
* inherited from interfaces
* inherited body from interface
* default arguments in an interface, implemented by a class delegate
* super call of a method with default argument

Also:
* inheritance from an interface and another interface descendant (KT-21968)
* inheritance through an intermediate interface

compiler/testData/codegen/box/defaultArguments/function/complexInheritance.kt

@@ -0,0 +1,15 @@
+// See KT-21968
+
+interface A {
+    fun f(cause: Int? = null): Boolean
+}
+
+open class B : A {
+    override fun f(cause: Int?): Boolean = true
+}
+
+class D : B(), A
+
+fun box(): String {
+    return if (D().f()) "OK" else "fail"
+}