dart2js cps: Fix some analyzer hints in the CPS backend.

pkg/compiler/lib/src/cps_ir/cps_ir_builder.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.
 
 library dart2js.ir_builder;
 
 import '../closure.dart' hide ClosureScope;
 import '../common.dart';
 import '../common/names.dart' show
     Names,
@@ skipping 635 matching lines @@
       _current = _current.plug(expr);
     }
   }
 
   /// Create and add a new [LetPrim] for [primitive].
   ir.Primitive addPrimitive(ir.Primitive primitive) {
     add(new ir.LetPrim(primitive));
     return primitive;
   }
 
-  ir.Primitive _continueWithExpression(ir.Expression build(ir.Continuation k)) {
-    ir.Parameter v = new ir.Parameter(null);
-    ir.Continuation k = new ir.Continuation([v]);
-    ir.Expression expression = build(k);
-    add(new ir.LetCont(k, expression));
-    return v;
-  }
-
   ir.Primitive _buildInvokeStatic(Element element,
                                   Selector selector,
                                   List<ir.Primitive> arguments,
                                   SourceInformation sourceInformation) {
     assert(!element.isLocal);
     assert(!element.isInstanceMember);
     assert(isOpen);
     return addPrimitive(
         new ir.InvokeStatic(element, selector, arguments, sourceInformation));
   }
@@ skipping 2250 matching lines @@
 }
 
 class SwitchCaseInfo {
   final List<ir.Primitive> constants = <ir.Primitive>[];
   final SubbuildFunction buildBody;
 
   SwitchCaseInfo(this.buildBody);
 
   void addConstant(ir.Primitive constant) => constants.add(constant);
 }