Avoiding creating strings for canonicalization

pkg/compiler/lib/src/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 dart2js.compiler_base;
 
 import 'dart:async' show EventSink, Future;
 
 import '../compiler_new.dart' as api;
 import 'closure.dart' as closureMapping show ClosureTask;
@@ skipping 456 matching lines @@
    * Get an [Uri] pointing to a patch for the dart: library with
    * the given path. Returns null if there is no patch.
    */
   Uri resolvePatchUri(String dartLibraryPath);
 
   Future runInternal(Uri uri) {
     // TODO(ahe): This prevents memory leaks when invoking the compiler
     // multiple times. Implement a better mechanism where we can store
     // such caches in the compiler and get access to them through a
     // suitably maintained static reference to the current compiler.
-    StringToken.canonicalizedSubstrings.clear();
+    StringToken.canonicalizer.clear();
     Selector.canonicalizedValues.clear();
 
     // The selector objects held in static fields must remain canonical.
     for (Selector selector in Selectors.ALL) {
       Selector.canonicalizedValues
           .putIfAbsent(selector.hashCode, () => <Selector>[])
           .add(selector);
     }
 
     assert(uri != null || options.analyzeOnly);
@@ skipping 1473 matching lines @@
   _ElementScanner(this.scanner);
   void scanLibrary(LibraryElement library) => scanner.scanLibrary(library);
   void scanUnit(CompilationUnitElement unit) => scanner.scan(unit);
 }
 
 class _EmptyEnvironment implements Environment {
   const _EmptyEnvironment();
 
   String valueOf(String key) => null;
 }