Remove the need for functionSignature.

sdk/lib/_internal/compiler/implementation/dart_backend/tree_ir_builder.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 tree_ir_builder;
 
 import '../dart2jslib.dart' as dart2js;
+import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
 import 'tree_ir_nodes.dart';
 
 /**
  * Builder translates from CPS-based IR to direct-style Tree.
  *
  * A call `Invoke(fun, cont, args)`, where cont is a singly-referenced
  * non-exit continuation `Cont(v, body)` is translated into a direct-style call
  * whose value is bound in the continuation body:
@@ skipping 414 matching lines @@
         translateArguments(node.keys),
         translateArguments(node.values));
   }
 
   FunctionDefinition makeSubFunction(cps_ir.FunctionDefinition function) {
     return new Builder.inner(this).build(function);
   }
 
   Node visitCreateFunction(cps_ir.CreateFunction node) {
     FunctionDefinition def = makeSubFunction(node.definition);
-    FunctionSignature signature = node.definition.element.functionSignature;
-    bool hasReturnType = !signature.type.returnType.treatAsDynamic;
+    FunctionType type = node.definition.element.type;
+    bool hasReturnType = !type.returnType.treatAsDynamic;
     if (hasReturnType) {
       // This function cannot occur in expression context.
       // The successor will be filled in by visitLetPrim.
       return new FunctionDeclaration(getVariable(node), def, null);
     } else {
       return new FunctionExpression(def);
     }
   }
 
   Expression visitParameter(cps_ir.Parameter node) {
     // Continuation parameters are not visited (continuations themselves are
     // not visited yet).
     compiler.internalError(compiler.currentElement, 'Unexpected IR node.');
     return null;
   }
 
   Expression visitContinuation(cps_ir.Continuation node) {
     // Until continuations with multiple uses are supported, they are not
     // visited.
     compiler.internalError(compiler.currentElement, 'Unexpected IR node.');
     return null;
   }
 
   Expression visitIsTrue(cps_ir.IsTrue node) {
     return getVariableReference(node.value);
   }
 }