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

pkg/compiler/lib/src/js_emitter/registry.dart

-// Copyright (c) 2014, 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 dart2js.js_emitter.program_builder;
-
-/// A Fragment maps [LibraryElement]s to their [Element]s.
-///
-/// Fundamentally, this class nicely encapsulates a
-/// `Map<LibraryElement, List<Element>>`.
-class Fragment {
-  final Map<LibraryElement, List<Element>> _mapping =
-      <LibraryElement, List<Element>>{};
-
-  // It is very common to access the same library multiple times in a row, so
-  // we cache the last access.
-  LibraryElement _lastLibrary;
-  List<Element> _lastElements;
-
-  /// A unique name representing this fragment.
-  final String name;
-  final OutputUnit outputUnit;
-
-  Fragment.main(this.outputUnit) : name = "";
-
-  Fragment.deferred(this.outputUnit, this.name) {
-    assert(name != "");
-  }
-
-  void add(LibraryElement library, Element element) {
-    if (_lastLibrary != library) {
-      _lastLibrary = library;
-      _lastElements = _mapping.putIfAbsent(library, () => <Element>[]);
-    }
-    _lastElements.add(element);
-  }
-
-  int get length => _mapping.length;
-
-  void forEach(void f(LibraryElement library, List<Element> elements)) {
-    _mapping.forEach(f);
-  }
-}
-
-/// Keeps track of all elements and holders.
-///
-/// This class assigns each registered element to its [Fragment] (which are in
-/// bijection with [OutputUnit]s).
-///
-/// Registered holders are assigned a name.
-class Registry {
-  final Compiler _compiler;
-  final Map<String, Holder> _holdersMap = <String, Holder>{};
-  final Map<OutputUnit, Fragment> _deferredFragmentsMap =
-      <OutputUnit, Fragment>{};
-
-  DeferredLoadTask get _deferredLoadTask => _compiler.deferredLoadTask;
-  Iterable<Holder> get holders => _holdersMap.values;
-  Iterable<Fragment> get deferredFragments => _deferredFragmentsMap.values;
-  // Add one for the main fragment.
-  int get fragmentCount => _deferredFragmentsMap.length + 1;
-
-  Fragment mainFragment;
-
-  Registry(this._compiler);
-
-  bool get _isProgramSplit => _deferredLoadTask.isProgramSplit;
-  OutputUnit get _mainOutputUnit => _deferredLoadTask.mainOutputUnit;
-
-  Fragment _mapUnitToFragment(OutputUnit targetUnit) {
-    if (mainFragment == null) {
-      mainFragment = new Fragment.main(_deferredLoadTask.mainOutputUnit);
-    }
-    if (!_isProgramSplit) {
-      assert(targetUnit == _deferredLoadTask.mainOutputUnit);
-      return mainFragment;
-    }
-    if (targetUnit == _mainOutputUnit) return mainFragment;
-    String name = targetUnit.name;
-    return _deferredFragmentsMap.putIfAbsent(
-        targetUnit, () => new Fragment.deferred(targetUnit, name));
-  }
-
-  /// Adds all elements to their respective libraries in the correct fragment.
-  void registerElements(OutputUnit outputUnit, List<Element> elements) {
-    Fragment targetFragment = _mapUnitToFragment(outputUnit);
-    for (Element element in Elements.sortedByPosition(elements)) {
-      targetFragment.add(element.library, element);
-    }
-  }
-
-  Holder registerHolder(String name) {
-    return _holdersMap.putIfAbsent(
-        name,
-        () => new Holder(name, _holdersMap.length));
-  }
-}