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

tests/compiler/dart2js/mock_compiler.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.
 
 #library('mock_compiler');
 
 #import("dart:uri");
 
 #import("../../../lib/compiler/implementation/elements/elements.dart");
 #import("../../../lib/compiler/implementation/leg.dart");
 #import('../../../lib/compiler/implementation/source_file.dart');
 #import("../../../lib/compiler/implementation/tree/tree.dart");
 #import("../../../lib/compiler/implementation/util/util.dart");
 #import('../../../lib/compiler/compiler.dart', prefix: 'api');
 #import("parser_helper.dart");
 
 class WarningMessage {
   Node node;
   Message message;
   WarningMessage(this.node, this.message);
 
   toString() => message.toString();
 }
 
-const String DEFAULT_HELPERLIB = @'''
+const String DEFAULT_HELPERLIB = r'''
   lt() {} add(var a, var b) {} sub() {} mul() {} div() {} tdiv() {} mod() {}
   neg() {} shl() {} shr() {} eq() {} le() {} gt() {} ge() {}
   or() {} and() {} not() {} eqNull(a) {} eqq() {}
   ltB() {} leB() {} eqB() {} gtB() {} geB() {} eqNullB(a) {}
   $throw(x) { return x; }
   iae(x) { throw x; } ioore(x) { throw x; }
   guard$array(x) { return x; }
   guard$num(x) { return x; }
   guard$string(x) { return x; }
   guard$stringOrArray(x) { return x; }
   index(a, index) {}
   indexSet(a, index, value) {}
   setRuntimeTypeInfo(a, b) {}
   getRuntimeTypeInfo(a) {}
   stringTypeCheck(x) {}
   interface JavaScriptIndexingBehavior {}
   S() {}
   assert(a){}''';
 
-const String DEFAULT_INTERCEPTORSLIB = @'''
+const String DEFAULT_INTERCEPTORSLIB = r'''
   add$1(receiver, value) {}
   get$length(receiver) {}
   filter(receiver, predicate) {}
   removeLast(receiver) {}
   iterator(receiver) {}
   next(receiver) {}
   hasNext(receiver) {}''';
 
-const String DEFAULT_CORELIB = @'''
+const String DEFAULT_CORELIB = r'''
   print(var obj) {}
   interface int extends num {}
   interface double extends num {}
   class bool {}
   class String {}
   class Object {}
   interface num {}
   class Function {}
   class List {}
   class Closure {}
@@ skipping 147 matching lines @@
     });
   }
 }
 
 LibraryElement mockLibrary(Compiler compiler, String source) {
   Uri uri = new Uri.fromComponents(scheme: "source");
   var library = new LibraryElement(new Script(uri, new MockFile(source)));
   importLibrary(library, compiler.coreLibrary, compiler);
   return library;
 }