Convert raw strings in compiler

lib/compiler/implementation/dart_backend/backend.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.
 
 const bool REMOVE_ASSERTS = false;
 
 class ElementAst {
   final Node ast;
   final TreeElements treeElements;
 
@@ skipping 203 matching lines @@
     // interfaces, most probably for interfaces of literals.
     final fixedMemberNames = new Set<String>();
     for (final library in compiler.libraries.getValues()) {
       if (!library.isPlatformLibrary) continue;
       for (final element in library.localMembers) {
         if (element is ClassElement) {
           ClassElement classElement = element;
           for (final member in classElement.localMembers) {
             final name = member.name.slowToString();
             // Skip operator names.
-            if (name.startsWith(@'operator$')) continue;
+            if (name.startsWith(r'operator$')) continue;
             // Fetch name of named constructors and factories if any,
             // otherwise store regular name.
             // TODO(antonm): better way to analyze the name.
-            fixedMemberNames.add(name.split(@'$').last());
+            fixedMemberNames.add(name.split(r'$').last());
           }
         }
         // Even class names are added due to a delicate problem we have:
         // if one imports dart:core with a prefix, we cannot tell prefix.name
         // from dynamic invocation (alas!).  So we'd better err on preserving
         // those names.
         fixedMemberNames.add(element.name.slowToString());
       }
     }
     // TODO(antonm): TypeError.srcType and TypeError.dstType are defined in
@@ skipping 212 matching lines @@
 }
 
 compareElements(e0, e1) {
   int result = compareBy((e) => e.getLibrary().uri.toString())(e0, e1);
   if (result != 0) return result;
   return compareBy((e) => e.position().charOffset)(e0, e1);
 }
 
 List<Element> sortElements(Collection<Element> elements) =>
     sorted(elements, compareElements);