Use shared implementation of Stopwatch.

dart/frog/leg/warnings.dart

Index: dart/frog/leg/warnings.dart
diff --git a/dart/frog/leg/warnings.dart b/dart/frog/leg/warnings.dart
index db5fdc19242144239edf388be9a9644119ac6f24..01cd9d0b73521f8f6df95fa4fc095b9777f9c841 100644
--- a/dart/frog/leg/warnings.dart
+++ b/dart/frog/leg/warnings.dart
@@ -50,6 +50,8 @@ class MessageKind {
       "'Object' does not have a superclass");
   static final CANNOT_FIND_CONSTRUCTOR = const MessageKind(
       'cannot find constructor #{1}');
+  static final CANNOT_FIND_CONSTRUCTOR2 = const MessageKind(
+      'cannot find constructor #{1} or #{2}');
   static final CYCLIC_CLASS_HIERARCHY = const MessageKind(
       '#{1} creates a cycle in the class hierarchy');
   static final INVALID_RECEIVER_IN_INITIALIZER = const MessageKind(
@@ -114,6 +116,9 @@ class MessageKind {
   static final CANNOT_INSTANTIATE_INTERFACE = const MessageKind(
       "cannot instantiate interface '#{1}'");
 
+  static final NO_DEFAULT_CLASS = const MessageKind(
+      "no default class on enclosing interface '#{1}'");
+
   toString() => template;
 }