Delete dart2js specific private library code

tool/input_sdk/private/native_helper.dart

Index: tool/input_sdk/private/native_helper.dart
diff --git a/tool/input_sdk/private/native_helper.dart b/tool/input_sdk/private/native_helper.dart
index 69e1392db9271b540abe5dfacf660014f30db325..3a1007a496bddaf5983cf548a9bb5829f038a0fc 100644
--- a/tool/input_sdk/private/native_helper.dart
+++ b/tool/input_sdk/private/native_helper.dart
@@ -5,40 +5,6 @@
 part of _js_helper;
 
 
-// TODO(ngeoffray): stop using this method once our optimizers can
-// change str1.contains(str2) into str1.indexOf(str2) != -1.
-bool contains(String userAgent, String name) {
-  return JS('int', '#.indexOf(#)', userAgent, name) != -1;
-}
-
-int arrayLength(List array) {
-  return JS('int', '#.length', array);
-}
-
-arrayGet(List array, int index) {
-  return JS('var', '#[#]', array, index);
-}
-
-void arraySet(List array, int index, var value) {
-  JS('var', '#[#] = #', array, index, value);
-}
-
-propertyGet(var object, String property) {
-  return JS('var', '#[#]', object, property);
-}
-
-bool callHasOwnProperty(var function, var object, String property) {
-  return JS('bool', '#.call(#, #)', function, object, property);
-}
-
-void propertySet(var object, String property, var value) {
-  JS('var', '#[#] = #', object, property, value);
-}
-
-getPropertyFromPrototype(var object, String name) {
-  return JS('var', 'Object.getPrototypeOf(#)[#]', object, name);
-}
-
 /**
  * Sets a JavaScript property on an object.
  */