Fix two bugs in the simple types inferrer:

tests/compiler/dart2js/simple_inferrer_final_field3_test.dart

+// Copyright (c) 2013, 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.
+
+// Test that we are analyzing field parameters correctly.
+
+import 'compiler_helper.dart';
+import 'parser_helper.dart';
+
+const String TEST = """
+
+class A {
+  final dynamicField;
+  A() : dynamicField = 42;
+  A.bar(this.dynamicField);
+}
+
+main() {
+  new A();
+  new A.bar('foo');
+}
+""";
+
+void main() {
+  Uri uri = new Uri.fromComponents(scheme: 'source');
+  var compiler = compilerFor(TEST, uri);
+  compiler.runCompiler(uri);
+  var typesInferrer = compiler.typesTask.typesInferrer;
+
+  checkFieldTypeInClass(String className, String fieldName, type) {
+    var cls = findElement(compiler, className);
+    var element = cls.lookupLocalMember(buildSourceString(fieldName));
+    Expect.equals(type, typesInferrer.typeOf[element]);
+  }
+
+  checkFieldTypeInClass('A', 'dynamicField', compiler.dynamicClass);
+}