Patches to support Dart VM patch files in dart2js.

sdk/lib/internal/symbol.dart

Index: sdk/lib/internal/symbol.dart
diff --git a/sdk/lib/internal/symbol.dart b/sdk/lib/internal/symbol.dart
index 21d976b119e423d42842c6a07d5dfc9169911427..73ac334f345cf1309f8440d42456bff21ec148d8 100644
--- a/sdk/lib/internal/symbol.dart
+++ b/sdk/lib/internal/symbol.dart
@@ -117,7 +117,7 @@ class Symbol implements core.Symbol {
     return 0x1fffffff & (arbitraryPrime * _name.hashCode);
   }
 
-  toString() => 'Symbol("$_name")';
+  external String toString();
 
   /// Platform-private accessor which cannot be called from user libraries.
   static String getName(Symbol symbol) => symbol._name;
@@ -142,4 +142,6 @@ class Symbol implements core.Symbol {
   static bool isValidSymbol(String name) {
     return (name.isEmpty || symbolPattern.hasMatch(name));
   }
+
+  external static getUnmangledName(Symbol symbol);
 }