Revert "Move dart2js from sdk/lib/_internal/compiler to pkg/compiler"

pkg/compiler/lib/src/scanner/parser_task.dart

-// Copyright (c) 2011, 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.
-
-part of scanner;
-
-class ParserTask extends CompilerTask {
-  ParserTask(Compiler compiler) : super(compiler);
-  String get name => 'Parser';
-
-  Node parse(ElementX element) {
-    return measure(() => element.parseNode(compiler));
-  }
-
-  Node parseCompilationUnit(Token token) {
-    return measure(() {
-      NodeListener listener = new NodeListener(compiler, null);
-      Parser parser = new Parser(listener);
-      parser.parseUnit(token);
-      Node result = listener.popNode();
-      assert(listener.nodes.isEmpty);
-      return result;
-    });
-  }
-}