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

tests/language/language_dart2js.status

 # 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.
 
 [ $compiler == dart2js || $compiler == dart2dart ]
 # VM specific tests that should not be run by dart2js.
 *vm_test: Skip
 *vm_negative_test: Skip
 
 [ $compiler == dart2js && $checked ]
@@ skipping 34 matching lines @@
 # problems in compile time constants.
 compile_time_constant_checked_test/02: Fail, OK
 
 [ $compiler == dart2js && $host_unchecked ]
 metadata_test: Fail # Metadata on type parameters not supported.
 
 [ $compiler == dart2js && $host_checked ]
 metadata_test: Crash # Metadata on type parameters not supported.
 
 [ $compiler == dart2js ]
-raw_string_test: Fail
 prefix_new_test: Fail # New library syntax not supported
 infinity_test: Fail # Issue 4984
 positive_bit_operations_test: Fail # (floitsch): This will be fixed when dart2js uses unsigned input for >>.
 
 class_literal_test/03: Fail # Calling a nonexistent static is not a compile time error anymore.
 class_literal_test/04: Fail # Calling a nonexistent static is not a compile time error anymore.
 class_literal_test/08: Fail # Calling a nonexistent static is not a compile time error anymore.
 class_literal_test/09: Fail # Calling a nonexistent static is not a compile time error anymore.
 class_literal_test/15: Fail # Calling a nonexistent static is not a compile time error anymore.
 class_literal_test/16: Fail # Calling a nonexistent static is not a compile time error anymore.
@@ skipping 231 matching lines @@
 
 
 [ $compiler == dart2js && $runtime == none ]
 *: Fail, Pass # TODO(ahe): Triage these tests.
 
 
 [ $compiler == dart2js && $runtime == ff ]
 call_through_getter_test: Fail # Expected: ObjectNotClosureException got: Instance of 'TypeError'
 call_through_null_getter_test: Fail # Expected: ObjectNotClosureException got: Instance of 'TypeError'
 double_to_string_as_fixed_test: Fail
-raw_string_test: Fail
 
 
 [ $compiler == dart2js && $runtime == ie ]
 call_through_getter_test: Fail
 call_through_null_getter_test: Fail
 div_by_zero_test: Fail
 double_to_string_as_fixed_test: Fail
 expect_test: Fail
 factory3_test: Fail
 local_function_test: Fail
 stack_overflow_test: Fail
 type_checks_in_factory_method_test: Fail
 
 
 [ $compiler == dart2js && $runtime == safari ]
 arithmetic_test: Skip # BUG(3492): Times out.
 call_through_getter_test: Fail # Expected: ObjectNotClosureException got: Instance of 'TypeError'
 call_through_null_getter_test: Fail # Expected: ObjectNotClosureException got: Instance of 'TypeError'
 closure3_test: Fail # Uncaught error: Instance of 'TypeError'
 method_invocation_test: Fail # Uncaught error: Instance of 'TypeError'
 null_pointer_exception_test: Fail # Uncaught error: Instance of 'TypeError'
 string_interpolate_npe_test: Fail # Uncaught error: Instance of 'TypeError'