dart2js cps: Generate direct field accesses a build-time.

pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.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_task;
 
 import '../closure.dart' as closurelib;
 import '../closure.dart' hide ClosureScope;
 import '../constants/expressions.dart';
 import '../dart_types.dart';
@@ skipping 2169 matching lines @@
 
   FunctionElement get throwTypeErrorHelper => _backend.getThrowTypeError();
 
   ClassElement get nullClass => _compiler.nullClass;
 
   DartType unaliasType(DartType type) => type.unalias(_compiler);
 
   TypeMask getTypeMaskForForeign(NativeBehavior behavior) {
     return TypeMaskFactory.fromNativeBehavior(behavior, _compiler);
   }
+
+  FieldElement locateSingleField(Selector selector, TypeMask type) {
+    return _compiler.world.locateSingleField(selector, type);
+  }
 }
 
 /// IR builder specific to the JavaScript backend, coupled to the [JsIrBuilder].
 class JsIrBuilderVisitor extends IrBuilderVisitor {
   JavaScriptBackend get backend => compiler.backend;
 
   /// Result of closure conversion for the current body of code.
   ///
   /// Will be initialized upon entering the body of a function.
   /// It is computed by the [ClosureTranslator].
@@ skipping 1073 matching lines @@
   }
 
   processSetStatic(ir.SetStatic node) {
     node.body = replacementFor(node.body);
   }
 
   processContinuation(ir.Continuation node) {
     node.body = replacementFor(node.body);
   }
 }