Make several tests running on JS backend.

compiler/testData/codegen/box/casts/mutableCollections/reifiedAsWithMutable.kt

@@ -1,10 +1,5 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_RUNTIME
 
-import java.util.*
-
 class Itr : Iterator<String> by ArrayList<String>().iterator()
 class MItr : MutableIterator<String> by ArrayList<String>().iterator()
 class LItr : ListIterator<String> by ArrayList<String>().listIterator()
@@ -46,7 +41,7 @@ inline fun <reified T> reifiedAsFailsWithCCE(x: Any, operation: String) {
     try {
         x as T
     }
-    catch (e: java.lang.ClassCastException) {
+    catch (e: ClassCastException) {
         return
     }
     catch (e: Throwable) {