Make CompilerTask independent of compiler.

tests/compiler/dart2js/exit_code_test.dart

 // Copyright (c) 2013, 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.
 
 // Test the exit code of dart2js in case of exceptions, errors, warnings, etc.
 
 
 import 'dart:async';
 import 'dart:io' show Platform;
 
@@ skipping 119 matching lines @@
   @override
   withCurrentElement(Element element, f()) {
     return super.withCurrentElement(element, () {
       compiler.test('Compiler.withCurrentElement');
       return f();
     });
   }
 }
 
 class TestScanner extends ScannerTask {
+  final TestCompiler compiler;
+
   TestScanner(TestCompiler compiler)
-      : super(compiler, compiler.dietParser);
-
-  TestCompiler get compiler => super.compiler;
+      : compiler = compiler,
+        super(compiler.dietParser, compiler.reporter, compiler.measurer);
 
   void scanElements(CompilationUnitElement compilationUnit) {
     compiler.test('ScannerTask.scanElements');
     super.scanElements(compilationUnit);
   }
 }
 
 class TestResolver extends ResolverTask {
   TestResolver(TestCompiler compiler, ConstantCompiler constantCompiler)
       : super(compiler, constantCompiler);
@@ skipping 127 matching lines @@
 
       expected = _expectedExitCode(
           beforeRun: tests[marker], fatalWarnings: true);
       totalExpectedErrors += expected.length;
       await testExitCodes(marker, expected, ['--fatal-warnings']);
     }
 
     Expect.equals(totalExpectedErrors, checkedResults);
   });
 }