Extension method support to move us closer to a valid List implementation.

tool/input_sdk/lib/core/list.dart

Index: tool/input_sdk/lib/core/list.dart
diff --git a/tool/input_sdk/lib/core/list.dart b/tool/input_sdk/lib/core/list.dart
index d4f6cfac81d7ac9122b1edbaf971d03b31d1915b..2ce69e1667da21e7931e101de92b435e64218996 100644
--- a/tool/input_sdk/lib/core/list.dart
+++ b/tool/input_sdk/lib/core/list.dart
@@ -51,7 +51,10 @@ part of dart.core;
  * directly or through iterating an [Iterable] that is backed by the list, will
  * break the iteration.
  */
+@SupportJsExtensionMethod()
+@JsPeerInterface(name: 'Array')

[Jacob, 2015/04/02 20:07:03]

the idea for 
@JsPeerInterface
is that all classes that implement List
automatically get a JS mixin that implements the JavaScript 
Array class.
A bit magical but it makes for nice 2 way interop for these classes instead of
interop that is nice in the dart->js direction and ugly in the reverse
direction.
The mixin for Array would look something like

class JsArrayMixin implements List {
  void append(value) { add(value); }
  void slice(?????) { ????; }
  ....
}

[Jennifer Messerly, 2015/04/03 16:25:27]

yeah, that's really nice.

 abstract class List<E> implements Iterable<E>, EfficientLength {
+  // Method that needs to be mixed in to all Dart subclasses that implement
   /**
    * Creates a list of the given length.
    *