Spelling fixes e to i.

tests/compiler/dart2js_extra/js_array_index_error_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// Test that optimized JSArray indexers enerate the same error as dynamically
+// Test that optimized JSArray indexers generate the same error as dynamically
 // dispatched calls.
 
 import 'package:expect/expect.dart';
 
 @NoInline()
 @AssumeDynamic()
 confuse(x) => x;
 
 Error getError(action(), name, part) {
   try {
@@ skipping 301 matching lines @@
 
   variableIndexSetEmpty(0, 'zero index');
   variableIndexSetEmpty(10, 'small index');
   variableIndexSetEmpty(-1, 'negative index');
   variableIndexSetEmpty(HUGE, 'huge index');
 
   variableIndexSetNonempty(10, 'small index');
   variableIndexSetNonempty(-1, 'negative index');
   variableIndexSetNonempty(HUGE, 'huge index');
 }