dart2js cps: Clean up and avoid processing unreachable code.

pkg/compiler/lib/src/tree_ir/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 '../common.dart';
 import '../constants/values.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
 import '../elements/elements.dart';
@@ skipping 482 matching lines @@
               getVariableUse(node.entries[index].key),
               getVariableUse(node.entries[index].value));
         })
     );
   }
 
   FunctionDefinition makeSubFunction(cps_ir.FunctionDefinition function) {
     return createInnerBuilder().buildFunction(function);
   }
 
-  Expression visitCreateFunction(cps_ir.CreateFunction node) {
-    FunctionDefinition def = makeSubFunction(node.definition);
-    return new FunctionExpression(def);
-  }
-
   Expression visitReifyRuntimeType(cps_ir.ReifyRuntimeType node) {
     return new ReifyRuntimeType(
         getVariableUse(node.value), node.sourceInformation);
   }
 
   Expression visitReadTypeVariable(cps_ir.ReadTypeVariable node) {
     return new ReadTypeVariable(
         node.variable,
         getVariableUse(node.target),
         node.sourceInformation);
@@ skipping 184 matching lines @@
     --enclosingFunctions;
   }
 
   @override
   visitInterpolatedNode(js.InterpolatedNode node) {
     if (enclosingFunctions > 0) {
       found = true;
     }
   }
 }