Convert raw strings to new syntax

tests/language/adjacent_const_string_literals_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.
 
 
 class Conster {
   const Conster(this.value);
 
   final value;
 
   toString() {
     return value.toString();
   }
 }
 
 main() {
   testEmpty();
   testInterpolation();
   testMultiline();
 }
 
 testEmpty() {
   Expect.equals("", (const Conster("" "" "")).toString());
   Expect.equals("", (const Conster("" '' "")).toString());
-  Expect.equals("", (const Conster("" "" @"")).toString());
+  Expect.equals("", (const Conster("" "" r"")).toString());
 
   Expect.equals("a", (const Conster("a" "")).toString());
   Expect.equals("a", (const Conster("a" '')).toString());
-  Expect.equals("a", (const Conster("a" @'')).toString());
+  Expect.equals("a", (const Conster("a" r'')).toString());
 
   Expect.equals("b", (const Conster('b' "")).toString());
   Expect.equals("b", (const Conster('b' '')).toString());
-  Expect.equals("b", (const Conster('b' @'')).toString());
+  Expect.equals("b", (const Conster('b' r'')).toString());
 
-  Expect.equals("c", (const Conster(@'c' "")).toString());
-  Expect.equals("c", (const Conster(@'c' '')).toString());
-  Expect.equals("c", (const Conster(@'c' @'')).toString());
+  Expect.equals("c", (const Conster(r'c' "")).toString());
+  Expect.equals("c", (const Conster(r'c' '')).toString());
+  Expect.equals("c", (const Conster(r'c' r'')).toString());
 
   Expect.equals("a", (const Conster("" "a")).toString());
   Expect.equals("a", (const Conster("" 'a')).toString());
-  Expect.equals("a", (const Conster("" @'a')).toString());
+  Expect.equals("a", (const Conster("" r'a')).toString());
 
   Expect.equals("b", (const Conster('' "b")).toString());
   Expect.equals("b", (const Conster('' 'b')).toString());
-  Expect.equals("b", (const Conster('' @'b')).toString());
+  Expect.equals("b", (const Conster('' r'b')).toString());
 
-  Expect.equals("c", (const Conster(@'' "c")).toString());
-  Expect.equals("c", (const Conster(@'' 'c')).toString());
-  Expect.equals("c", (const Conster(@'' @'c')).toString());
+  Expect.equals("c", (const Conster(r'' "c")).toString());
+  Expect.equals("c", (const Conster(r'' 'c')).toString());
+  Expect.equals("c", (const Conster(r'' r'c')).toString());
 }
 
 const s = "a";
 
 testInterpolation() {
-  Expect.equals(@"ab", (const Conster("$s" "b")).toString());
-  Expect.equals(@"ab", (const Conster('$s' "b")).toString());
-  Expect.equals(@"$sb", (const Conster(@'$s' "b")).toString());
+  Expect.equals(r"ab", (const Conster("$s" "b")).toString());
+  Expect.equals(r"ab", (const Conster('$s' "b")).toString());
+  Expect.equals(r"$sb", (const Conster(r'$s' "b")).toString());
 
-  Expect.equals(@"-a-b", (const Conster("-$s-" "b")).toString());
-  Expect.equals(@"-a-b", (const Conster('-$s-' "b")).toString());
-  Expect.equals(@"-$s-b", (const Conster(@'-$s-' "b")).toString());
+  Expect.equals(r"-a-b", (const Conster("-$s-" "b")).toString());
+  Expect.equals(r"-a-b", (const Conster('-$s-' "b")).toString());
+  Expect.equals(r"-$s-b", (const Conster(r'-$s-' "b")).toString());
 
-  Expect.equals(@"ba", (const Conster('b' "$s")).toString());
-  Expect.equals(@"ba", (const Conster('b' '$s')).toString());
-  Expect.equals(@"b$s", (const Conster('b' @'$s')).toString());
+  Expect.equals(r"ba", (const Conster('b' "$s")).toString());
+  Expect.equals(r"ba", (const Conster('b' '$s')).toString());
+  Expect.equals(r"b$s", (const Conster('b' r'$s')).toString());
 
-  Expect.equals(@"b-a-", (const Conster('b' "-$s-")).toString());
-  Expect.equals(@"b-a-", (const Conster('b' '-$s-')).toString());
-  Expect.equals(@"b-$s-", (const Conster('b' @'-$s-')).toString());
+  Expect.equals(r"b-a-", (const Conster('b' "-$s-")).toString());
+  Expect.equals(r"b-a-", (const Conster('b' '-$s-')).toString());
+  Expect.equals(r"b-$s-", (const Conster('b' r'-$s-')).toString());
 }
 
 testMultiline() {
   Expect.equals("abe",
                 (const Conster("a"
                 "b"
                 "e")).toString());
   Expect.equals("a b e",
                 (const Conster("a "
                 "b "
                 "e")).toString());
   Expect.equals("a b e",
                 (const Conster("a"
                 " b"
                 " e")).toString());
 
   Expect.equals("abe", (const Conster("""
 a""" "b" "e")).toString());
   Expect.equals("a b e", (const Conster("""
 a""" " b" " e")).toString());
 
   Expect.equals("abe", (const Conster("""
 a""" """
 b""" """
 e""")).toString());
 }