Replace @native with external in tests

js/js.translator/testData/box/nameClashes/nativeAndTopLevelFunction.kt

@@ -1,6 +1,6 @@
 package test
 
-@native fun foo(ignore: dynamic): String
+external fun foo(ignore: dynamic): String
 
 @JsName("foo")
 fun foo() = "K"

js/js.translator/testData/box/nameClashes/nativeDeclarationAndLocalVar.kt

@@ -1,8 +1,8 @@
 package test
 
-@native fun foo(): dynamic
+external fun foo(): dynamic
 
-@native fun bar(): dynamic
+external fun bar(): dynamic
 
 fun box(): String {
     val foo = "local foo;"