Refactor BackendHelpers to make 'find' methods private.

pkg/compiler/lib/src/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
 import 'dart:math' as math;
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart' show Compiler;
 import '../constants/constant_system.dart';
@@ skipping 2921 matching lines @@
     }
 
     if (namedParameters.isEmpty) {
       var arguments = [returnType];
       if (!parameterTypes.isEmpty || !optionalParameterTypes.isEmpty) {
         arguments.add(new js.ArrayInitializer(parameterTypes));
       }
       if (!optionalParameterTypes.isEmpty) {
         arguments.add(new js.ArrayInitializer(optionalParameterTypes));
       }
-      push(js.js('#(#)', [accessHelper('buildFunctionType'), arguments]));
+      push(js.js('#(#)', [accessHelper(helpers.buildFunctionType), arguments]));
     } else {
       var arguments = [
         returnType,
         new js.ArrayInitializer(parameterTypes),
         new js.ObjectInitializer(namedParameters)
       ];
-      push(js.js('#(#)', [accessHelper('buildNamedFunctionType'), arguments]));
+      push(js.js(
+          '#(#)', [accessHelper(helpers.buildNamedFunctionType), arguments]));
     }
   }
 
   void visitTypeInfoReadRaw(HTypeInfoReadRaw node) {
     use(node.inputs[0]);
     js.Expression receiver = pop();
     push(js.js(r'#.#', [receiver, backend.namer.rtiFieldName]));
   }
 
   void visitTypeInfoReadVariable(HTypeInfoReadVariable node) {
@@ skipping 110 matching lines @@
     for (HInstruction type in node.inputs) {
       use(type);
       typeArguments.add(pop());
     }
     InterfaceType type = node.dartType;
     ClassElement cls = type.element;
     var arguments = [backend.emitter.typeAccess(cls)];
     if (!typeArguments.isEmpty) {
       arguments.add(new js.ArrayInitializer(typeArguments));
     }
-    push(js.js('#(#)',
-        [accessHelper('buildInterfaceType', arguments.length), arguments]));
+    push(js.js('#(#)', [
+      accessHelper(helpers.buildInterfaceType, arguments.length),
+      arguments
+    ]));
   }
 
   void visitVoidType(HVoidType node) {
-    push(js.js('#()', accessHelper('getVoidRuntimeType')));
+    push(js.js('#()', accessHelper(helpers.getVoidRuntimeType)));
   }
 
   void visitDynamicType(HDynamicType node) {
-    push(js.js('#()', accessHelper('getDynamicRuntimeType')));
+    push(js.js('#()', accessHelper(helpers.getDynamicRuntimeType)));
   }
 
-  js.PropertyAccess accessHelper(String name, [int argumentCount = 0]) {
-    Element helper = helpers.findHelper(name);
+  js.PropertyAccess accessHelper(FunctionEntity helper,
+      [int argumentCount = 0]) {
     if (helper == null) {
       // For mocked-up tests.
-      return js.js('(void 0).$name');
+      return js.js('(void 0).dummy');
     }
     registry.registerStaticUse(new StaticUse.staticInvoke(
         helper, new CallStructure.unnamed(argumentCount)));
     return backend.emitter.staticFunctionAccess(helper);
   }
 
   @override
   void visitRef(HRef node) {
     visit(node.value);
   }
 }