Do not evaluate on-demand to prevent breaking the deferred loading task

tests/compiler/dart2js_extra/deferred/deferred_constant_dependency_evaluation_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.
+
+// This is a regression test for dartbug.com/26406. We test that the deferred
+// loader analyzer doesn't trip over constant expression evaluation.
+//
+// Today the task uses constant values to calculate dependencies, and only uses
+// those values that were previously computed by resolution. A change to compute
+// the value on-demmand made the deferred task evaluate more expressions,
+// including expressions with free variables (which can't be evaluated). See the
+// dartbug.com/26406 for details on how we plan to make the task more robust.
+
+// import is only used to trigger the deferred task
+import 'deferred_class_library.dart' deferred as lib;
+
+class A {
+  final int x;
+
+  const A(bool foo)
+      // The deferred task would crash trying to compute the value here, where
+      // [foo] is a free variable.
+      : x = foo ? 1 : 0;
+}
+
+main() => const A(true);