some stylistic fixes

Author: zloirock

packages/core-js/internals/async-iterator-create-proxy.js

@@ -79,7 +79,7 @@ var createAsyncIteratorProxyPrototype = function (IS_ITERATOR) {
         var returnMethod, result;
         var completion = perform(function () {
           if (state.inner) try {
-            iteratorClose(state.inner.iterator, 'return');
+            iteratorClose(state.inner.iterator, 'normal');
           } catch (error) {
             return iteratorClose(iterator, 'throw', error);
           }

packages/core-js/internals/iterator-create-proxy.js

@@ -42,11 +42,11 @@ var createIteratorProxyPrototype = function (IS_ITERATOR) {
         return returnMethod ? call(returnMethod, iterator) : createIterResultObject(undefined, true);
       }
       if (state.inner) try {
-        iteratorClose(state.inner.iterator, 'return');
+        iteratorClose(state.inner.iterator, 'normal');
       } catch (error) {
         return iteratorClose(iterator, 'throw', error);
       }
-      iteratorClose(iterator, 'return');
+      iteratorClose(iterator, 'normal');
       return createIterResultObject(undefined, true);
     }
   });