Update dart:mirrors to use Symbol.

dart/runtime/lib/symbol_patch.dart

Index: dart/runtime/lib/symbol_patch.dart
diff --git a/dart/runtime/lib/symbol_patch.dart b/dart/runtime/lib/symbol_patch.dart
index 67713487371ad5a5843055b030a3f6b09f229c1e..4359019fd74dc7b26f49aede99fd9c875fe2f169 100644
--- a/dart/runtime/lib/symbol_patch.dart
+++ b/dart/runtime/lib/symbol_patch.dart
@@ -2,34 +2,44 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-patch  class Symbol {
-  final String _name;
+patch class Symbol {
   /* patch */ const Symbol(String name)
-    : this._name = _validate(name);
-
+      : this._name = _validate(name);
 
   static final RegExp _validationPattern =
-      new RegExp(r'^[a-zA-Z$][a-zA-Z$0-9_]*=?');
+      new RegExp(r'^(?:[a-zA-Z$][a-zA-Z$0-9_]*\.)*(?:[a-zA-Z$][a-zA-Z$0-9_]*=?|'
+                 r'-|'
+                 r'unary-|'
+                 r'\[\]=|'
+                 r'~|'
+                 r'==|'
+                 r'\[\]|'
+                 r'\*|'
+                 r'/|'
+                 r'%|'
+                 r'~/|'
+                 r'\+|'
+                 r'<<|'
+                 r'>>|'
+                 r'>=|'
+                 r'>|'
+                 r'<=|'
+                 r'<|'
+                 r'&|'
+                 r'\^|'
+                 r'\|'
+                 r')$');
 
   static _validate(String name) {
     if (name is! String) throw new ArgumentError('name must be a String');
-    if (name.isEmpty) return;
+    if (name.isEmpty) return name;
     if (name.startsWith('_')) {
       throw new ArgumentError('"$name" is a private identifier');
     }
     if (!_validationPattern.hasMatch(name)) {
       throw new ArgumentError(
-	  '"$name" is not an identifier or an empty String');
+          '"$name" is not an identifier or an empty String');
     }
     return name;
   }
-
-  /* patch */ bool operator ==(other) {
-    return other is Symbol && _name == other._name;
-  }
-
-  /* patch */ int get hashCode {
-    const arbitraryPrime = 664597;
-    return 0x1fffffff & (arbitraryPrime * _name.hashCode);
-  }
 }