Add @JSName annotation for native fields and methods.

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

Index: sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
index 161ebf1e5b89006302e41c8adcff9c1744840a3d..c96ac2f1caefa44730a53d5a149138464b2aa716 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
@@ -546,7 +546,7 @@ class Primitives {
       if (end <= kMaxApply) {
         subarray = array;
       } else {
-        subarray = JS('List<int>', r'array.slice(#, #)',
+        subarray = JS('=List', r'array.slice(#, #)',
                       i, i + kMaxApply < end ? i + kMaxApply : end);
       }
       result = JS('String', '# + String.fromCharCode.apply(#, #)',
@@ -1212,6 +1212,23 @@ class Returns {
 }
 
 /**
+ * A metadata annotation placed on native methods and fields of native classes
+ * to specify the JavaScript name.
+ *
+ * This example declares a Dart field + getter + setter called `$dom_title` that
+ * corresponds to the JavaScript property `title`.
+ *
+ *     class Docmument native "*Foo" {
+ *       @JSName('title')
+ *       String $dom_title;
+ *     }
+ */
+class JSName {
+  final String name;
+  const JSName(this.name);
+}
+
+/**
  * Represents the type of Null. The compiler treats this specially.
  * TODO(lrn): Null should be defined in core. It's a class, like int.
  * It just happens to act differently in assignability tests and,