Ensure uniqueness of global names.

dart/lib/compiler/implementation/namer.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer {
   final Compiler compiler;
 
@@ skipping 88 matching lines @@
   }
 
   String getterName(LibraryElement lib, SourceString name) {
     // We dynamically create getters from the field-name. The getter name must
     // therefore be derived from the instance field-name.
     String fieldName = safeName(privateName(lib, name));
     return 'get\$$fieldName';
   }
 
   String getFreshGlobalName(String proposedName) {
-    int usedCount = usedGlobals[proposedName];
-    if (usedCount === null) {
-      // No element with this name has been used before.
-      usedGlobals[proposedName] = 1;
-      return proposedName;
-    } else {
+    String name = proposedName;
+    int count = usedGlobals[name];
+    if (count !== null) {
       // Not the first time we see this name. Append a number to make it unique.
-      String name;
       do {
-        usedCount++;
-        name = '$proposedName$usedCount';
+        name = '$proposedName${count++}';
       } while (usedGlobals[name] !== null);
-      usedGlobals[proposedName] = usedCount;
-      return name;
+      // Record the count in case we see this name later. We
+      // frequently see names multiple times, as all our closures use
+      // the same name for their class.
+      usedGlobals[proposedName] = count;
     }
+    usedGlobals[name] = 0;
+    return name;
   }
 
   static final String LIBRARY_PREFIX = "lib";
 
   /**
    * Returns a preferred JS-id for the given top-level or static element.
    * The returned id is guaranteed to be a valid JS-id.
    */
   String _computeGuess(Element element) {
     assert(!element.isInstanceMember());
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   }
 
   String safeName(String name) {
     if (jsReserved.contains(name) || name.startsWith('\$')) {
       name = "\$$name";
       assert(!jsReserved.contains(name));
     }
     return name;
   }
 }