Fix inferrer bug in the presence of compound assignments and unresolved fields in a generative cons…

tests/language/inferrer_this_access_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.
+
+import "package:expect/expect.dart";
+
+class A {
+  var fisk;
+  A() {
+    // dart2js's inferrer used to not recognize the following call to
+    // be on [this].
+    fisk--;
+    fisk = 42;
+  }
+}
+
+class B {
+  var a;
+  B() {
+    hest = 54;
+    a = 42;
+  } 
+}
+
+class C extends B {
+  set hest(value) {
+    return a + 42;
+  }
+}
+
+main() {
+  Expect.throws(() => new A(), (e) => e is NoSuchMethodError);
+  Expect.throws(() => new C(), (e) => e is NoSuchMethodError);
+}