fix generic const canonicalization bug

frog/gen.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.
 
 /**
  * Top level generator object for writing code and keeping track of
  * dependencies.
  *
  * Should have two compilation models, but only one implemented so far.
  *
@@ skipping 93 matching lines @@
     hasStatics = true;
     var fullname = "${field.declaringType.jsname}.${field.jsname}";
     if (!globals.containsKey(fullname)) {
       globals[fullname] = new GlobalValue.fromStatic(
           field, fieldValue, dependencies);
     }
     return globals[fullname];
   }
 
   GlobalValue globalForConst(EvaluatedValue exp, List<Value> dependencies) {
-    var code = exp.canonicalCode;
-    if (!globals.containsKey(code)) {
-      globals[code] =
+    // Include type name to ensure unique constants - this matches
+    // the code above that includes the type name for static fields.
+    var key = exp.type.jsname + ':' + exp.canonicalCode;
+    if (!globals.containsKey(key)) {
+      globals[key] =
         new GlobalValue.fromConst(globals.length, exp, dependencies);
     }
-    return globals[code];
+    assert(globals[key].type == exp.type);
+    return globals[key];
   }
 
   writeTypes(Library lib) {
     if (lib.isWritten) return;
 
     // Do this first to be safe in the face of circular refs.
     lib.isWritten = true;
 
     // Ensure all imports have been written.
     for (var import in lib.imports) {
@@ skipping 2264 matching lines @@
       result.add(new Value(world.varType, '\$$i', null, /*needsTemp:*/false));
     }
     for (int i = bareCount; i < length; i++) {
       var name = getName(i);
       if (name == null) name = '\$$i';
       result.add(new Value(world.varType, name, null, /*needsTemp:*/false));
     }
     return new Arguments(nodes, result);
   }
 }