issue 4817 fixed. Implemented raw strings with 'r' instead of '@' for dart2js

tests/compiler/dart2js/class_codegen_test.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.
 // Test that parameters keep their names in the output.
 
 #import("compiler_helper.dart");
 #import("parser_helper.dart");
 
-const String TEST_ONE = @"""
+const String TEST_ONE = r"""
 class A { }
 class B { }
 
 main() {
   new A();
   new B();
 }
 """;
 
-const String TEST_TWO = @"""
+const String TEST_TWO = r"""
 class A { }
 class B extends A { }
 
 main() {
   new A();
   new B();
 }
 """;
 
-const String TEST_THREE = @"""
+const String TEST_THREE = r"""
 class B extends A { }
 class A { }
 
 main() {
   new B();
   new A();
 }
 """;
 
-const String TEST_FOUR = @"""
+const String TEST_FOUR = r"""
 class A {
   var x;
 }
 
 class B extends A {
   var y;
   var z;
 }
 
 main() {
   new B();
 }
 """;
 
-const String TEST_FIVE = @"""
+const String TEST_FIVE = r"""
 class A {
   var x;
   A(x) : this.x = x {}
 }
 
 main() {
   new A(3);
 }
 """;
 
 twoClasses() {
   String generated = compileAll(TEST_ONE);
   Expect.isTrue(generated.contains('\$.A = {"":\n [],\n "super": "Object"'));
   Expect.isTrue(generated.contains('\$.B = {"":\n [],\n "super": "Object"'));
 }
 
 subClass() {
   checkOutput(String generated) {
     Expect.isTrue(generated.contains('\$.A = {"":\n [],\n "super": "Object"'));
     Expect.isTrue(generated.contains('\$.B = {"":\n [],\n "super": "A"'));
   }
 
   checkOutput(compileAll(TEST_TWO));
   checkOutput(compileAll(TEST_THREE));
 }
 
 fieldTest() {
   String generated = compileAll(TEST_FOUR);
   print(generated);
-  Expect.isTrue(generated.contains(@"""
+  Expect.isTrue(generated.contains(r"""
 $.B = {"":
  ["y", "z", "x"],
  "super": "A"
 }"""));
 }
 
 constructor1() {
   String generated = compileAll(TEST_FIVE);
-  Expect.isTrue(generated.contains(@"new $.A(x);"));
+  Expect.isTrue(generated.contains(r"new $.A(x);"));
 }
 
 main() {
   twoClasses();
   subClass();
   fieldTest();
   constructor1();
 }