Revert "Adapt String interface for Utf16."

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

Index: sdk/lib/_internal/compiler/implementation/lib/js_string.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/js_string.dart b/sdk/lib/_internal/compiler/implementation/lib/js_string.dart
index 381a690564ac2c86ee075b4d996308cbc0bd2828..d0d857c2feb5996c99446a27bf1c90fcb659af97 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/js_string.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/js_string.dart
@@ -13,9 +13,7 @@ part of _interceptors;
 class JSString implements String {
   const JSString();
 
-  int charCodeAt(index) => codeUnitAt(index);
-
-  int codeUnitAt(int index) {
+  int charCodeAt(index) {
     if (index is !num) throw new ArgumentError(index);
     if (index < 0) throw new RangeError.value(index);
     if (index >= length) throw new RangeError.value(index);
@@ -149,14 +147,6 @@ class JSString implements String {
     return result;
   }
 
-  Iterable<int> get codeUnits {
-    throw new UnimplementedError("String.codeUnits");
-  }
-
-  Iterable<int> get runes {
-    throw new UnimplementedError("String.runes");
-  }
-
   int indexOf(String other, [int start = 0]) {
     checkNull(other);
     if (start is !int) throw new ArgumentError(start);