Use entities in class_stub_generator.

pkg/compiler/lib/src/kernel/kernel_visitor.dart

 // Copyright (c) 2016, 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.md file.
 
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/frontend/accessors.dart'
     show
         Accessor,
         IndexAccessor,
         NullAwarePropertyAccessor,
@@ skipping 891 matching lines @@
   }
 
   @override
   ir.NullLiteral visitLiteralNull(LiteralNull node) {
     return new ir.NullLiteral();
   }
 
   @override
   ir.Expression visitLiteralString(LiteralString node) {
     if (node.dartString == null) return new ir.InvalidExpression();
-    return associateNode(new ir.StringLiteral(node.dartString.slowToString()),
-        node);
+    return associateNode(
+        new ir.StringLiteral(node.dartString.slowToString()), node);
   }
 
   @override
   ir.SymbolLiteral visitLiteralSymbol(LiteralSymbol node) {
     var result = new ir.SymbolLiteral(node.slowNameString);
     return associateNode(result, node);
   }
 
   @override
   visitMetadata(Metadata node) {
@@ skipping 1935 matching lines @@
       : this(null, true, node, initializers);
 
   accept(ir.Visitor v) => throw "unsupported";
 
   visitChildren(ir.Visitor v) => throw "unsupported";
 
   String toString() {
     return "IrFunction($kind, $isConstructor, $node, $initializers)";
   }
 }