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

pkg/compiler/lib/src/scanner/scanner_task.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.
-
-part of scanner;
-
-class ScannerTask extends CompilerTask {
-  ScannerTask(Compiler compiler) : super(compiler);
-  String get name => 'Scanner';
-
-  void scanLibrary(LibraryElement library) {
-    CompilationUnitElement compilationUnit = library.entryCompilationUnit;
-    String canonicalUri = library.canonicalUri.toString();
-    String resolvedUri = compilationUnit.script.readableUri.toString();
-    if (canonicalUri == resolvedUri) {
-      compiler.log("Scanning library $canonicalUri");
-    } else {
-      compiler.log("Scanning library $canonicalUri ($resolvedUri)");
-    }
-    scan(compilationUnit);
-  }
-
-  void scan(CompilationUnitElement compilationUnit) {
-    measure(() {
-      scanElements(compilationUnit);
-    });
-  }
-
-  void scanElements(CompilationUnitElement compilationUnit) {
-    Script script = compilationUnit.script;
-    Token tokens = new Scanner(script.file,
-        includeComments: compiler.preserveComments).tokenize();
-    if (compiler.preserveComments) {
-      tokens = compiler.processAndStripComments(tokens);
-    }
-    compiler.dietParser.dietParse(compilationUnit, tokens);
-  }
-
-  /**
-   * Returns the tokens for the [source].
-   *
-   * The [StringScanner] implementation works on strings that end with a '0'
-   * value ('\x00'). If [source] does not end with '0', the string is copied
-   * before scanning.
-   */
-  Token tokenize(String source) {
-    return measure(() {
-      return new StringScanner.fromString(source, includeComments: false)
-          .tokenize();
-    });
-  }
-}
-
-class DietParserTask extends CompilerTask {
-  DietParserTask(Compiler compiler) : super(compiler);
-  final String name = 'Diet Parser';
-
-  dietParse(CompilationUnitElement compilationUnit, Token tokens) {
-    measure(() {
-      Function idGenerator = compiler.getNextFreeClassId;
-      ElementListener listener =
-          new ElementListener(compiler, compilationUnit, idGenerator);
-      PartialParser parser = new PartialParser(listener);
-      parser.parseUnit(tokens);
-    });
-  }
-}