Update dart2js unit tests to dart_parser and dart_scanner.

tests/compiler/dart2js/scanner_test.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.
 
 import "package:expect/expect.dart";
-import 'package:compiler/src/scanner/utf8_bytes_scanner.dart';
-import 'package:compiler/src/tokens/precedence_constants.dart';
-import 'package:compiler/src/tokens/token.dart';
-import 'package:compiler/src/util/characters.dart';
+import 'package:dart_scanner/dart_scanner.dart';
+import 'package:dart_scanner/src/characters.dart';
+import 'package:dart_scanner/src/precedence.dart';
 import 'dart:typed_data';
 
+
 Token scan(List<int> bytes) {
   List<int> zeroTerminated = new Uint8List(bytes.length + 1);
   zeroTerminated.setRange(0, bytes.length, bytes);
   zeroTerminated[bytes.length] = 0;
-  return new Utf8BytesScanner.fromBytes(zeroTerminated).tokenize();
+  return new Utf8BytesScanner(zeroTerminated).tokenize();
 }
 
 Token scanUTF8(List<int> bytes) {
   int l = bytes.length;
   List<int> stringLiteral = new Uint8List(l + 3);
   stringLiteral[0] = 0x27; // single quote
   stringLiteral[l + 1] = 0x27; // single quote
   // The bytes given to the scanner must be 0-terminated.
   stringLiteral[l + 2] = $EOF;
   for (int i = 0; i < l; i++) {
     stringLiteral[i + 1] = bytes[i];
   }
-  return new Utf8BytesScanner.fromBytes(stringLiteral).tokenize();
+  return new Utf8BytesScanner(stringLiteral).tokenize();
 }
 
 bool isRunningOnJavaScript() => identical(1, 1.0);
 
 main() {
   // Google favorite: "Îñţérñåţîöñåļîžåţîờñ".
   Token token = scanUTF8([
     0xc3,
     0x8e,
     0xc3,
@@ skipping 162 matching lines @@
     0x20,
     0x57,
     0x6f,
     0x72,
     0x6c,
     0x64,
     0x21
   ]);
   Expect.equals(token.info, EOF_INFO); // Treated as a comment.
 }