Relanding: avoiding creating strings for canonicalization

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index dd3249e13d6f3e0cccd5fe5e1234255f3bb97dec..807b4e2bd9a862e696c281a93524b26d8a25c94d 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -467,7 +467,7 @@ abstract class Compiler implements LibraryLoaderListener {
     // 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.