Allow use of deferred type-literals in non-constant contexts.

pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart

 // Copyright (c) 2014, 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.
 
 library backend_ast_emitter;
 
 import '../tree_ir/tree_ir_nodes.dart' as tree;
 import 'backend_ast_nodes.dart';
 import '../constants/expressions.dart';
 import '../constants/values.dart';
@@ skipping 1261 matching lines @@
     } else {
       return exp.falseExp.accept(this);
     }
   }
 
   @override
   Expression visitUnary(UnaryConstantExpression exp,
                         BuilderContext<Statement> context) {
     return handlePrimitiveConstant(exp.value);
   }
+
+  @override
+  Expression visitDeferred(DeferredConstantExpression exp,
+                           BuilderContext<Statement> context) {
+    return exp.expression.accept(this);
+  }
 }
 
 /// Moves function parameters into a separate variable if one of its uses is
 /// shadowed by an inner function parameter.
 /// This artifact is necessary because function parameters cannot be renamed.
 class UnshadowParameters extends tree.RecursiveVisitor {
 
   /// Maps parameter names to their bindings.
   Map<String, tree.Variable> environment = <String, tree.Variable>{};
 
@@ skipping 67 matching lines @@
       : super(name, ElementKind.VARIABLE, enclosingElement, variables, null);
 
   ExecutableElement get executableContext => enclosingElement;
 
   ExecutableElement get memberContext => executableContext.memberContext;
 
   bool get isLocal => true;
 
   LibraryElement get implementationLibrary => enclosingElement.library;
 }