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);
  }
  });