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

tests/compiler/dart2js/field_codegen_test.dart

Index: tests/compiler/dart2js/field_codegen_test.dart
diff --git a/tests/compiler/dart2js/field_codegen_test.dart b/tests/compiler/dart2js/field_codegen_test.dart
index abae13753a644f029efee8f52d922590baa850b0..80ca722feb22c84c78c8483cd6c9491cadfb86fe 100644
--- a/tests/compiler/dart2js/field_codegen_test.dart
+++ b/tests/compiler/dart2js/field_codegen_test.dart
@@ -6,13 +6,13 @@
 #import("compiler_helper.dart");
 #import("parser_helper.dart");
 
-const String TEST_NULL0 = @"""
+const String TEST_NULL0 = r"""
 class A { static var x; }
 
 main() { return A.x; }
 """;
 
-const String TEST_NULL1 = @"""
+const String TEST_NULL1 = r"""
 var x;
 
 main() { return x; }