[K/JS] Add file-to-file compilation ^KT-6168 Fixed

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsClass.kt

@@ -9,7 +9,7 @@ import org.jetbrains.kotlin.js.common.Symbol
 
 class JsClass(
     private var name: JsName? = null,
-    var baseClass: JsNameRef? = null,
+    var baseClass: JsExpression? = null,
     var constructor: JsFunction? = null,
     val members: MutableList<JsFunction> = mutableListOf()
 ) : JsLiteral(), HasName {

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsExport.kt

@@ -18,10 +18,7 @@ class JsExport(
         object All : Subject()
     }
 
-    class Element(
-        val name: JsNameRef,
-        val alias: JsName?
-    )
+    class Element(val name: JsNameRef, val alias: JsName? = null)
 
     override fun accept(visitor: JsVisitor) {
         visitor.visitExport(this)