Add --verify-ir flag to dartk and test.py.

pkg/kernel/lib/text/ast_to_text.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 file.
 library kernel.ast_to_text;
 
 import '../ast.dart';
 import '../import_table.dart';
 import '../type_propagation/type_propagation.dart';
 
 class Namer<T> {
@@ skipping 74 matching lines @@
 String debugVariableDeclarationName(VariableDeclaration node) {
   return node.name ?? globalDebuggingNames.nameVariable(node);
 }
 
 String debugNodeToString(Node node) {
   StringBuffer buffer = new StringBuffer();
   new Printer(buffer, syntheticNames: globalDebuggingNames).writeNode(node);
   return '$buffer';
 }
 
+String programToString(Program node) {
+  StringBuffer buffer = new StringBuffer();
+  new Printer(buffer, syntheticNames: new NameSystem()).writeProgramFile(node);
+  return '$buffer';
+}
+
 class NameSystem {
   final Namer<VariableDeclaration> variables =
       new Namer<VariableDeclaration>('#t');
   final Namer<Member> members = new Namer<Member>('#m');
   final Namer<Class> classes = new Namer<Class>('#class');
   final Namer<Library> libraries = new Namer<Library>('#lib');
   final Namer<TypeParameter> typeParameters = new Namer<TypeParameter>('#T');
   final Namer<TreeNode> labels = new Namer<TreeNode>('#L');
   final Disambiguator<Library> prefixes = new Disambiguator<Library>();
 
@@ skipping 1424 matching lines @@
   }
   throw 'illegal ProcedureKind: $kind';
 }
 
 class ExpressionPrinter {
   final Printer writeer;
   final int minimumPrecedence;
 
   ExpressionPrinter(this.writeer, this.minimumPrecedence);
 }