Begin refactoring compiler out of diet parser and scanner

tests/compiler/dart2js/parser_helper.dart

Index: tests/compiler/dart2js/parser_helper.dart
diff --git a/tests/compiler/dart2js/parser_helper.dart b/tests/compiler/dart2js/parser_helper.dart
index d6e19538e6a5bf442b6c9266c3851559705c7942..193b58bf11c8726e3674b6feb60747ca19dc9934 100644
--- a/tests/compiler/dart2js/parser_helper.dart
+++ b/tests/compiler/dart2js/parser_helper.dart
@@ -7,6 +7,7 @@ library parser_helper;
 import "package:expect/expect.dart";
 
 import "package:compiler/src/elements/elements.dart";
+import 'package:compiler/src/id_generator.dart';
 import "package:compiler/src/tree/tree.dart";
 import "package:compiler/src/parser/element_listener.dart";
 import "package:compiler/src/parser/node_listener.dart";
@@ -138,6 +139,11 @@ class MockFile extends StringSourceFile {
       : super.fromName('<string>', text);
 }
 
+class _IdGenerator implements IdGenerator {
+  int _id = 0;
+  int getNextFreeId() => _id++;
+}
+
 var sourceCounter = 0;
 
 Link<Element> parseUnit(String text, Compiler compiler,
@@ -150,11 +156,10 @@ Link<Element> parseUnit(String text, Compiler compiler,
   }
   var script = new Script(uri, uri, new MockFile(text));
   var unit = new CompilationUnitElementX(script, library);
-  int id = 0;
   DiagnosticReporter reporter = compiler.reporter;
   ElementListener listener = new ElementListener(
       compiler.parsing.getScannerOptionsFor(library),
-      reporter, unit, () => id++);
+      reporter, unit, new _IdGenerator());
   PartialParser parser = new PartialParser(listener, new MockParserOptions());
   reporter.withCurrentElement(unit, () => parser.parseUnit(tokens));
   return unit.localMembers;