Update dart2js to use diagnostic kinds.

dart/lib/compiler/compiler.dart

Index: dart/lib/compiler/compiler.dart
diff --git a/dart/lib/compiler/compiler.dart b/dart/lib/compiler/compiler.dart
index 29f1d85e1a884be9f7bc705cf01cc96fbcc87092..3a15caf59805a600664f56a894ee3cc784a6d7e5 100644
--- a/dart/lib/compiler/compiler.dart
+++ b/dart/lib/compiler/compiler.dart
@@ -29,7 +29,7 @@ typedef Future<String> ReadStringFromUri(Uri uri);
  * diagnostic it is.
  */
 typedef void DiagnosticHandler(Uri uri, int begin, int end,
-                               String message, var kind);
+                               String message, Diagnostic kind);
 
 /**
  * Returns a future that completes to [script] compiled to JavaScript. If
@@ -71,34 +71,34 @@ class Diagnostic {
    * This means that the compiler can generate code that when executed
    * terminates execution.
    */
-  static final Diagnostic ERROR = const Diagnostic(1);
+  static final Diagnostic ERROR = const Diagnostic(1, 'error');
 
   /**
    * A warning as identified by the "Dart Programming Language
    * Specification" [http://www.dartlang.org/docs/spec/].
    */
-  static final Diagnostic WARNING = const Diagnostic(2);
+  static final Diagnostic WARNING = const Diagnostic(2, 'warning');
 
   /**
    * Any other warning that is not covered by [WARNING].
    */
-  static final Diagnostic LINT = const Diagnostic(4);
+  static final Diagnostic LINT = const Diagnostic(4, 'lint');
 
   /**
    * Informational messages.
    */
-  static final Diagnostic INFO = const Diagnostic(8);
+  static final Diagnostic INFO = const Diagnostic(8, 'info');
 
   /**
    * Informational messages that shouldn't be printed unless
    * explicitly requested by the user of a compiler.
    */
-  static final Diagnostic VERBOSE_INFO = const Diagnostic(16);
+  static final Diagnostic VERBOSE_INFO = const Diagnostic(16, 'verbose info');
 
   /**
    * An internal error in the compiler.
    */
-  static final Diagnostic CRASH = const Diagnostic(32);
+  static final Diagnostic CRASH = const Diagnostic(32, 'crash');
 
   /**
    * An [int] representation of this kind. The ordinals are designed
@@ -107,8 +107,15 @@ class Diagnostic {
   final int ordinal;
 
   /**
+   * The name of this kind.
+   */
+  final String name;
+
+  /**
    * This constructor is not private to support user-defined
    * diagnostic kinds.
    */
-  const Diagnostic(this.ordinal);
+  const Diagnostic(this.ordinal, this.name);
+
+  String toString() => name;
 }