Only set initializer fields as fields, not properties.

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 829 matching lines @@
           } else if (init is BinaryExpression
               && TokenKind.kindFromAssign(init.op.kind) == 0) {
 
             var left = init.x;
             if (!(left is DotExpression && left.self is ThisExpression
                 || left is VarExpression)) {
               world.error('invalid left side of initializer', left.span);
               continue;
             }
 
-            initializedFields.add(left.name.name);
-            var assign = _makeThisValue(null).set_(
-                this, left.name.name, left.name, visitValue(init.y));
-            writer.writeln('${assign.code};');
+            var f = method.declaringType.getMember(left.name.name);
+            if (f == null) {
+              world.error('bad initializer - no matching field', left.span);
+              continue;
+            } else if (!f.isField) {
+              world.error('"${left.name.name}" does not refer to a field',
+                  left.span);
+              continue;
+            }
+
+            initializedFields.add(f.name);
+            writer.writeln('this.${f.jsname} = ${visitValue(init.y).code};');
           } else {
             world.error('invalid initializer', init.span);
           }
         }
 
         if (initializerCall != null) {
           var target = _writeInitializerCall(initializerCall);
           if (!target.isSuper) {
             // when calling another constructor on the same class
             // no other initialization is allowed
@@ skipping 1362 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);
   }
 }