Add List.insert.

sdk/lib/_internal/compiler/implementation/lib/js_array.dart

 // Copyright (c) 2012, 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.
 
 part of _interceptors;
 
 /**
  * The interceptor class for [List]. The compiler recognizes this
  * class as an interceptor, and changes references to [:this:] to
  * actually use the receiver of the method, which is generated as an extra
  * argument added to each member.
  */
 class JSArray<E> implements List<E> {
   const JSArray();
 
   void add(E value) {
     checkGrowable(this, 'add');
     JS('void', r'#.push(#)', this, value);
   }
 
   E removeAt(int index) {
     if (index is !int) throw new ArgumentError(index);
     if (index < 0 || index >= length) {
       throw new RangeError.value(index);
     }
     checkGrowable(this, 'removeAt');
     return JS('var', r'#.splice(#, 1)[0]', this, index);
   }
 
+  void insertAt(int index, E value) {
+    if (index is !int) throw new ArgumentError(index);
+    if (index < 0 || index > length) {
+      throw new RangeError.value(index);
+    }
+    checkGrowable(this, 'insertAt');
+    JS('void', r'#.splice(#, 0, #)', this, index, value);
+  }
+
   E removeLast() {
     checkGrowable(this, 'removeLast');
     if (length == 0) throw new RangeError.value(-1);
     return JS('var', r'#.pop()', this);
   }
 
   void remove(Object element) {
     checkGrowable(this, 'remove');
     for (int i = 0; i < this.length; i++) {
       if (this[i] == element) {
@@ skipping 244 matching lines @@
     return JS('var', '#[#]', this, index);
   }
 
   void operator []=(int index, E value) {
     checkMutable(this, 'indexed set');
     if (index is !int) throw new ArgumentError(index);
     if (index >= length || index < 0) throw new RangeError.value(index);
     JS('void', r'#[#] = #', this, index, value);
   }
 }