Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/polymer/src/instance.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.
+
+part of polymer;
+
+/// Use this annotation to publish a property as an attribute.
+///
+/// You can also use [PublishedProperty] to provide additional information,
+/// such as automatically syncing the property back to the attribute.
+///
+/// For example:
+///
+///     class MyPlaybackElement extends PolymerElement {
+///       // This will be available as an HTML attribute, for example:
+///       //
+///       //     <my-playback volume="11">
+///       //
+///       // It will support initialization and data-binding via <template>:
+///       //
+///       //     <template>
+///       //       <my-playback volume="{{x}}">
+///       //     </template>
+///       //
+///       // If the template is instantiated or given a model, `x` will be
+///       // used for this field and updated whenever `volume` changes.
+///       @published
+///       double get volume => readValue(#volume);
+///       set volume(double newValue) => writeValue(#volume, newValue);
+///
+///       // This will be available as an HTML attribute, like above, but it
+///       // will also serialize values set to the property to the attribute.
+///       // In other words, attributes['volume2'] will contain a serialized
+///       // version of this field.
+///       @PublishedProperty(reflect: true)
+///       double get volume2 => readValue(#volume2);
+///       set volume2(double newValue) => writeValue(#volume2, newValue);
+///     }
+///
+/// **Important note**: the pattern using `readValue` and `writeValue`
+/// guarantees that reading the property will give you the latest value at any
+/// given time, even if change notifications have not been propagated.
+///
+/// We still support using @published on a field, but this will not
+/// provide the same guarantees, so this is discouraged. For example:
+///
+///       // Avoid this if possible. This will be available as an HTML
+///       // attribute too, but you might need to delay reading volume3 
+///       // asynchronously to guarantee that you read the latest value
+///       // set through bindings.
+///       @published double volume3;
+const published = const PublishedProperty();
+
+/// An annotation used to publish a field as an attribute. See [published].
+class PublishedProperty extends ObservableProperty {
+  /// Whether the property value should be reflected back to the HTML attribute.
+  final bool reflect;
+
+  const PublishedProperty({this.reflect: false});
+}
+
+/// Use this type to observe a property and have the method be called when it
+/// changes. For example:
+///
+///     @ObserveProperty('foo.bar baz qux')
+///     validate() {
+///       // use this.foo.bar, this.baz, and this.qux in validation
+///       ...
+///     }
+///
+/// Note that you can observe a property path, and more than a single property
+/// can be specified in a space-delimited list or as a constant List.
+class ObserveProperty {
+  final _names;
+
+  List<String> get names {
+    var n = _names;
+    // TODO(jmesserly): the bogus '$n' is to workaround a dart2js bug, otherwise
+    // it generates an incorrect call site.
+    if (n is String) return '$n'.split(' ');
+    if (n is! Iterable) {
+      throw new UnsupportedError('ObserveProperty takes either an Iterable of '
+          'names, or a space separated String, instead of `$n`.');
+    }
+    return n;
+  }
+
+  const ObserveProperty(this._names);
+}
+
+/// Use this to create computed properties that are updated automatically. The
+/// annotation includes a polymer expression that describes how this property
+/// value can be expressed in terms of the values of other properties. For
+/// example:
+///
+///     class MyPlaybackElement extends PolymerElement {
+///       @observable int x;
+///
+///       // Reading xTimes2 will return x * 2.
+///       @ComputedProperty('x * 2')
+///       int get xTimes2 => readValue(#xTimes2);
+///
+/// If the polymer expression is assignable, you can also define a setter for
+/// it. For example:
+///
+///       // Reading c will return a.b, writing c will update a.b.
+///       @ComputedProperty('a.b')
+///       get c => readValue(#c);
+///       set c(newValue) => writeValue(#c, newValue);
+///
+/// The expression can do anything that is allowed in a polymer expresssion,
+/// even making calls to methods in your element. However, dependencies that are
+/// only used within those methods and that are not visible in the polymer
+/// expression, will not be observed. For example:
+///
+///       // Because `x` only appears inside method `m`, we will not notice
+///       // that `d` has changed if `x` is modified. However, `d` will be
+///       // updated whenever `c` changes.
+///       @ComputedProperty('m(c)')
+///       get d => readValue(#d);
+///
+///       m(c) => c + x;
+class ComputedProperty {
+  /// A polymer expression, evaluated in the context of the custom element where
+  /// this annotation is used.
+  final String expression;
+
+  const ComputedProperty(this.expression);
+}
+
+/// Base class for PolymerElements deriving from HtmlElement.
+///
+/// See [Polymer].
+class PolymerElement extends HtmlElement with Polymer, Observable {
+  PolymerElement.created() : super.created() {
+    polymerCreated();
+  }
+}
+
+
+/// The mixin class for Polymer elements. It provides convenience features on
+/// top of the custom elements web standard.
+///
+/// If this class is used as a mixin,
+/// you must call `polymerCreated()` from the body of your constructor.
+abstract class Polymer implements Element, Observable, NodeBindExtension {
+
+  // TODO(jmesserly): should this really be public?
+  /// Regular expression that matches data-bindings.
+  static final bindPattern = new RegExp(r'\{\{([^{}]*)}}');
+
+  /// Like [document.register] but for Polymer elements.
+  ///
+  /// Use the [name] to specify custom elment's tag name, for example:
+  /// "fancy-button" if the tag is used as `<fancy-button>`.
+  ///
+  /// The [type] is the type to construct. If not supplied, it defaults to
+  /// [PolymerElement].
+  // NOTE: this is called "element" in src/declaration/polymer-element.js, and
+  // exported as "Polymer".
+  static void register(String name, [Type type]) {
+    //console.log('registering [' + name + ']');
+    if (type == null) type = PolymerElement;
+
+    _typesByName[name] = type;
+
+    // Dart note: here we notify JS of the element registration. We don't pass
+    // the Dart type because we will handle that in PolymerDeclaration.
+    // See _hookJsPolymerDeclaration for how this is done.
+    (js.context['Polymer'] as JsFunction).apply([name]);
+    (js.context['HTMLElement']['register'] as JsFunction).apply(
+        [name, js.context['HTMLElement']['prototype']]);
+  }
+
+  /// Register a custom element that has no associated `<polymer-element>`.
+  /// Unlike [register] this will always perform synchronous registration and
+  /// by the time this method returns the element will be available using
+  /// [document.createElement] or by modifying the HTML to include the element.
+  static void registerSync(String name, Type type,
+      {String extendsTag, Document doc, Node template}) {
+
+    // Our normal registration, this will queue up the name->type association.
+    register(name, type);
+
+    // Build a polymer-element and initialize it to register
+    if (doc == null) doc = document;
+    var poly = doc.createElement('polymer-element');
+    poly.attributes['name'] = name;
+    if (extendsTag != null) poly.attributes['extends'] = extendsTag;
+    if (template != null) poly.append(template);
+
+    // TODO(jmesserly): conceptually this is just:
+    //     new JsObject.fromBrowserObject(poly).callMethod('init')
+    //
+    // However doing it that way hits an issue with JS-interop in IE10: we get a
+    // JsObject that wraps something other than `poly`, due to improper caching.
+    // By reusing _polymerElementProto that we used for 'register', we can
+    // then call apply on it to invoke init() with the correct `this` pointer.
+    JsFunction init = _polymerElementProto['init'];
+    init.apply([], thisArg: poly);
+  }
+
+  // Warning for when people try to use `importElements` or `import`.
+  static const String _DYNAMIC_IMPORT_WARNING = 'Dynamically loading html '
+      'imports has very limited support right now in dart, see '
+      'http://dartbug.com/17873.';
+
+  /// Loads the set of HTMLImports contained in `node`. Returns a future that
+  /// resolves when all the imports have been loaded. This method can be used to
+  /// lazily load imports. For example, given a template:
+  ///
+  ///     <template>
+  ///       <link rel="import" href="my-import1.html">
+  ///       <link rel="import" href="my-import2.html">
+  ///     </template>
+  ///
+  ///     Polymer.importElements(template.content)
+  ///         .then((_) => print('imports lazily loaded'));
+  ///
+  /// Dart Note: This has very limited support in dart, http://dartbug.com/17873
+  // Dart Note: From src/lib/import.js For now proxy to the JS methods,
+  // because we want to share the loader with polymer.js for interop purposes.
+  static Future importElements(Node elementOrFragment) {
+    print(_DYNAMIC_IMPORT_WARNING);
+    var completer = new Completer();
+    js.context['Polymer'].callMethod('importElements',
+        [elementOrFragment, () => completer.complete()]);
+    return completer.future;
+  }
+
+  /// Loads an HTMLImport for each url specified in the `urls` array. Notifies
+  /// when all the imports have loaded by calling the `callback` function
+  /// argument. This method can be used to lazily load imports. For example,
+  /// For example,
+  ///
+  ///     Polymer.import(['my-import1.html', 'my-import2.html'])
+  ///         .then((_) => print('imports lazily loaded'));
+  ///
+  /// Dart Note: This has very limited support in dart, http://dartbug.com/17873
+  // Dart Note: From src/lib/import.js. For now proxy to the JS methods,
+  // because we want to share the loader with polymer.js for interop purposes.
+  static Future import(List urls) {
+    print(_DYNAMIC_IMPORT_WARNING);
+    var completer = new Completer();
+    js.context['Polymer'].callMethod('import',
+        [urls, () => completer.complete()]);
+    return completer.future;
+  }
+
+  /// Deprecated: Use `import` instead.
+  @deprecated
+  static Future importUrls(List urls) {
+    return import(urls);
+  }
+
+  static final Completer _onReady = new Completer();
+
+  /// Future indicating that the Polymer library has been loaded and is ready
+  /// for use.
+  static Future get onReady => _onReady.future;
+
+  /// Returns a list of elements that have had polymer-elements created but
+  /// are not yet ready to register. The list is an array of element
+  /// definitions.
+  static List<Element> get waitingFor =>
+      _Polymer.callMethod('waitingFor', [null]);
+
+  /// Forces polymer to register any pending elements. Can be used to abort
+  /// waiting for elements that are partially defined.
+  static forceReady([int timeout]) =>
+      _Polymer.callMethod('forceReady', [null, timeout]);
+
+  /// The most derived `<polymer-element>` declaration for this element.
+  PolymerDeclaration get element => _element;
+  PolymerDeclaration _element;
+
+  /// Deprecated: use [element] instead.
+  @deprecated PolymerDeclaration get declaration => _element;
+
+  Map<String, StreamSubscription> _namedObservers;
+  List<Bindable> _observers = [];
+
+  bool _unbound; // lazy-initialized
+  PolymerJob _unbindAllJob;
+
+  CompoundObserver _propertyObserver;
+  bool _readied = false;
+
+  JsObject _jsElem;
+
+  /// Returns the object that should be used as the event controller for
+  /// event bindings in this element's template. If set, this will override the
+  /// normal controller lookup.
+  // TODO(jmesserly): we need to use a JS-writable property as our backing
+  // store, because of elements such as:
+  // https://github.com/Polymer/core-overlay/blob/eeb14853/core-overlay-layer.html#L78
+  get eventController => _jsElem['eventController'];
+  set eventController(value) { _jsElem['eventController'] = value; }
+
+  bool get hasBeenAttached => _hasBeenAttached;
+  bool _hasBeenAttached = false;
+
+  /// Gets the shadow root associated with the corresponding custom element.
+  ///
+  /// This is identical to [shadowRoot], unless there are multiple levels of
+  /// inheritance and they each have their own shadow root. For example,
+  /// this can happen if the base class and subclass both have `<template>` tags
+  /// in their `<polymer-element>` tags.
+  // TODO(jmesserly): should expose this as an immutable map.
+  // Similar issue as $.
+  final Map<String, ShadowRoot> shadowRoots =
+      new LinkedHashMap<String, ShadowRoot>();
+
+  /// Map of items in the shadow root(s) by their [Element.id].
+  // TODO(jmesserly): various issues:
+  // * wrap in UnmodifiableMapView?
+  // * should we have an object that implements noSuchMethod?
+  // * should the map have a key order (e.g. LinkedHash or SplayTree)?
+  // * should this be a live list? Polymer doesn't, maybe due to JS limitations?
+  // Note: this is observable to support $['someId'] being used in templates.
+  // The template is stamped before $ is populated, so we need observation if
+  // we want it to be usable in bindings.
+  final Map<String, dynamic> $ = new ObservableMap<String, dynamic>();
+
+  /// Use to override the default syntax for polymer-elements.
+  /// By default this will be null, which causes [instanceTemplate] to use
+  /// the template's bindingDelegate or the [element.syntax], in that order.
+  PolymerExpressions get syntax => null;
+
+  bool get _elementPrepared => _element != null;
+
+  /// Retrieves the custom element name. It should be used instead
+  /// of localName, see: https://github.com/Polymer/polymer-dev/issues/26
+  String get _name {
+    if (_element != null) return _element.name;
+    var isAttr = attributes['is'];
+    return (isAttr == null || isAttr == '') ? localName : isAttr;
+  }
+
+  /// By default the data bindings will be cleaned up when this custom element
+  /// is detached from the document. Overriding this to return `true` will
+  /// prevent that from happening.
+  bool get preventDispose => false;
+
+  /// Properties exposed by this element.
+  // Dart note: unlike Javascript we can't override the original property on
+  // the object, so we use this mechanism instead to define properties. See more
+  // details in [_PropertyAccessor].
+  Map<Symbol, _PropertyAccessor> _properties = {};
+
+  /// Helper to implement a property with the given [name]. This is used for
+  /// normal and computed properties. Normal properties can provide the initial
+  /// value using the [initialValue] function. Computed properties ignore
+  /// [initialValue], their value is derived from the expression in the
+  /// [ComputedProperty] annotation that appears above the getter that uses this
+  /// helper.
+  readValue(Symbol name, [initialValue()]) {
+    var property = _properties[name];
+    if (property == null) {
+      var value;
+      // Dart note: most computed properties are created in advance in
+      // createComputedProperties, but if one computed property depends on
+      // another, the declaration order might matter. Rather than trying to
+      // register them in order, we include here also the option of lazily
+      // creating the property accessor on the first read.
+      var binding = _getBindingForComputedProperty(name);
+      if (binding == null) { // normal property
+        value = initialValue != null ? initialValue() : null;
+      } else {
+        value = binding.value;
+      }
+      property = _properties[name] = new _PropertyAccessor(name, this, value);
+    }
+    return property.value;
+  }
+
+  /// Helper to implement a setter of a property with the given [name] on a
+  /// polymer element. This can be used on normal properties and also on
+  /// computed properties, as long as the expression used for the computed
+  /// property is assignable (see [ComputedProperty]).
+  writeValue(Symbol name, newValue) {
+    var property = _properties[name];
+    if (property == null) {
+      // Note: computed properties are created in advance in
+      // createComputedProperties, so we should only need to create here
+      // non-computed properties.
+      property = _properties[name] = new _PropertyAccessor(name, this, null);
+    }
+    property.value = newValue;
+  }
+
+  /// If this class is used as a mixin, this method must be called from inside
+  /// of the `created()` constructor.
+  ///
+  /// If this class is a superclass, calling `super.created()` is sufficient.
+  void polymerCreated() {
+    var t = nodeBind(this).templateInstance;
+    if (t != null && t.model != null) {
+      window.console.warn('Attributes on $_name were data bound '
+          'prior to Polymer upgrading the element. This may result in '
+          'incorrect binding types.');
+    }
+    prepareElement();
+    if (!isTemplateStagingDocument(ownerDocument)) {
+      _makeElementReady();
+    }
+  }
+
+  /// *Deprecated* use [shadowRoots] instead.
+  @deprecated
+  ShadowRoot getShadowRoot(String customTagName) => shadowRoots[customTagName];
+
+  void prepareElement() {
+    if (_elementPrepared) {
+      window.console.warn('Element already prepared: $_name');
+      return;
+    }
+    _initJsObject();
+    // Dart note: get the corresponding <polymer-element> declaration.
+    _element = _getDeclaration(_name);
+    // install property storage
+    createPropertyObserver();
+    openPropertyObserver();
+    // install boilerplate attributes
+    copyInstanceAttributes();
+    // process input attributes
+    takeAttributes();
+    // add event listeners
+    addHostListeners();
+  }
+
+  /// Initialize JS interop for this element. For now we just initialize the
+  /// JsObject, but in the future we could also initialize JS APIs here.
+  _initJsObject() {
+    _jsElem = new JsObject.fromBrowserObject(this);
+  }
+
+  /// Deprecated: This is no longer a public method.
+  @deprecated
+  makeElementReady() => _makeElementReady();
+
+  _makeElementReady() {
+    if (_readied) return;
+    _readied = true;
+    createComputedProperties();
+
+    parseDeclarations(_element);
+    // NOTE: Support use of the `unresolved` attribute to help polyfill
+    // custom elements' `:unresolved` feature.
+    attributes.remove('unresolved');
+    // user entry point
+    _readyLog.info(() => '[$this]: ready');
+    ready();
+  }
+
+  /// Lifecycle method called when the element has populated it's `shadowRoot`,
+  /// prepared data-observation, and made itself ready for API interaction.
+  /// To wait until the element has been attached to the default view, use
+  /// [attached] or [domReady].
+  void ready() {}
+
+  /// Implement to access custom elements in dom descendants, ancestors,
+  /// or siblings. Because custom elements upgrade in document order,
+  /// elements accessed in `ready` or `attached` may not be upgraded. When
+  /// `domReady` is called, all registered custom elements are guaranteed
+  /// to have been upgraded.
+  void domReady() {}
+
+  void attached() {
+    if (!_elementPrepared) {
+      // Dart specific message for a common issue.
+      throw new StateError('polymerCreated was not called for custom element '
+          '$_name, this should normally be done in the .created() if Polymer '
+          'is used as a mixin.');
+    }
+
+    cancelUnbindAll();
+    if (!hasBeenAttached) {
+      _hasBeenAttached = true;
+      async((_) => domReady());
+    }
+  }
+
+  void detached() {
+    if (!preventDispose) asyncUnbindAll();
+  }
+
+  /// Walks the prototype-chain of this element and allows specific
+  /// classes a chance to process static declarations.
+  ///
+  /// In particular, each polymer-element has it's own `template`.
+  /// `parseDeclarations` is used to accumulate all element `template`s
+  /// from an inheritance chain.
+  ///
+  /// `parseDeclaration` static methods implemented in the chain are called
+  /// recursively, oldest first, with the `<polymer-element>` associated
+  /// with the current prototype passed as an argument.
+  ///
+  /// An element may override this method to customize shadow-root generation.
+  void parseDeclarations(PolymerDeclaration declaration) {
+    if (declaration != null) {
+      parseDeclarations(declaration.superDeclaration);
+      parseDeclaration(declaration.element);
+    }
+  }
+
+  /// Perform init-time actions based on static information in the
+  /// `<polymer-element>` instance argument.
+  ///
+  /// For example, the standard implementation locates the template associated
+  /// with the given `<polymer-element>` and stamps it into a shadow-root to
+  /// implement shadow inheritance.
+  ///
+  /// An element may override this method for custom behavior.
+  void parseDeclaration(Element elementElement) {
+    var template = fetchTemplate(elementElement);
+
+    if (template != null) {
+      var root = shadowFromTemplate(template);
+
+      var name = elementElement.attributes['name'];
+      if (name == null) return;
+      shadowRoots[name] = root;
+    }
+  }
+
+  /// Given a `<polymer-element>`, find an associated template (if any) to be
+  /// used for shadow-root generation.
+  ///
+  /// An element may override this method for custom behavior.
+  Element fetchTemplate(Element elementElement) =>
+      elementElement.querySelector('template');
+
+  /// Utility function that stamps a `<template>` into light-dom.
+  Node lightFromTemplate(Element template, [Node refNode]) {
+    if (template == null) return null;
+
+    // TODO(sorvell): mark this element as an event controller so that
+    // event listeners on bound nodes inside it will be called on it.
+    // Note, the expectation here is that events on all descendants
+    // should be handled by this element.
+    eventController = this;
+
+    // stamp template
+    // which includes parsing and applying MDV bindings before being
+    // inserted (to avoid {{}} in attribute values)
+    // e.g. to prevent <img src="images/{{icon}}"> from generating a 404.
+    var dom = instanceTemplate(template);
+    // append to shadow dom
+    if (refNode != null) {
+      append(dom);
+    } else {
+      insertBefore(dom, refNode);
+    }
+    // perform post-construction initialization tasks on ahem, light root
+    shadowRootReady(this);
+    // return the created shadow root
+    return dom;
+  }
+
+  /// Utility function that creates a shadow root from a `<template>`.
+  ///
+  /// The base implementation will return a [ShadowRoot], but you can replace it
+  /// with your own code and skip ShadowRoot creation. In that case, you should
+  /// return `null`.
+  ///
+  /// In your overridden method, you can use [instanceTemplate] to stamp the
+  /// template and initialize data binding, and [shadowRootReady] to intialize
+  /// other Polymer features like event handlers. It is fine to call
+  /// shadowRootReady with a node other than a ShadowRoot such as with `this`.
+  ShadowRoot shadowFromTemplate(Element template) {
+    if (template == null) return null;
+    // make a shadow root
+    var root = createShadowRoot();
+    // stamp template
+    // which includes parsing and applying MDV bindings before being
+    // inserted (to avoid {{}} in attribute values)
+    // e.g. to prevent <img src="images/{{icon}}"> from generating a 404.
+    var dom = instanceTemplate(template);
+    // append to shadow dom
+    root.append(dom);
+    // perform post-construction initialization tasks on shadow root
+    shadowRootReady(root);
+    // return the created shadow root
+    return root;
+  }
+
+  void shadowRootReady(Node root) {
+    // locate nodes with id and store references to them in this.$ hash
+    marshalNodeReferences(root);
+  }
+
+  /// Locate nodes with id and store references to them in [$] hash.
+  void marshalNodeReferences(Node root) {
+    if (root == null) return;
+    for (var n in (root as dynamic).querySelectorAll('[id]')) {
+      $[n.id] = n;
+    }
+  }
+
+  void attributeChanged(String name, String oldValue, String newValue) {
+    if (name != 'class' && name != 'style') {
+      attributeToProperty(name, newValue);
+    }
+  }
+
+  // TODO(jmesserly): this could be a top level method.
+  /// Returns a future when `node` changes, or when its children or subtree
+  /// changes.
+  ///
+  /// Use [MutationObserver] if you want to listen to a stream of changes.
+  Future<List<MutationRecord>> onMutation(Node node) {
+    var completer = new Completer();
+    new MutationObserver((mutations, observer) {
+      observer.disconnect();
+      completer.complete(mutations);
+    })..observe(node, childList: true, subtree: true);
+    return completer.future;
+  }
+
+  // copy attributes defined in the element declaration to the instance
+  // e.g. <polymer-element name="x-foo" tabIndex="0"> tabIndex is copied
+  // to the element instance here.
+  void copyInstanceAttributes() {
+    _element._instanceAttributes.forEach((name, value) {
+      attributes.putIfAbsent(name, () => value);
+    });
+  }
+
+  void takeAttributes() {
+    if (_element._publishLC == null) return;
+    attributes.forEach(attributeToProperty);
+  }
+
+  /// If attribute [name] is mapped to a property, deserialize
+  /// [value] into that property.
+  void attributeToProperty(String name, String value) {
+    // try to match this attribute to a property (attributes are
+    // all lower-case, so this is case-insensitive search)
+    var decl = propertyForAttribute(name);
+    if (decl == null) return;
+
+    // filter out 'mustached' values, these are to be
+    // replaced with bound-data and are not yet values
+    // themselves.
+    if (value == null || value.contains(Polymer.bindPattern)) return;
+
+    final currentValue = smoke.read(this, decl.name);
+
+    // deserialize Boolean or Number values from attribute
+    var type = decl.type;
+    if ((type == Object || type == dynamic) && currentValue != null) {
+      // Attempt to infer field type from the current value.
+      type = currentValue.runtimeType;
+    }
+    final newValue = deserializeValue(value, currentValue, type);
+
+    // only act if the value has changed
+    if (!identical(newValue, currentValue)) {
+      // install new value (has side-effects)
+      smoke.write(this, decl.name, newValue);
+    }
+  }
+
+  /// Return the published property matching name, or null.
+  // TODO(jmesserly): should we just return Symbol here?
+  smoke.Declaration propertyForAttribute(String name) {
+    final publishLC = _element._publishLC;
+    if (publishLC == null) return null;
+    return publishLC[name];
+  }
+
+  /// Convert representation of [value] based on [type] and [currentValue].
+  Object deserializeValue(String value, Object currentValue, Type type) =>
+      deserialize.deserializeValue(value, currentValue, type);
+
+  String serializeValue(Object value) {
+    if (value == null) return null;
+
+    if (value is bool) {
+      return _toBoolean(value) ? '' : null;
+    } else if (value is String || value is num) {
+      return '$value';
+    }
+    return null;
+  }
+
+  void reflectPropertyToAttribute(String path) {
+    // TODO(sjmiles): consider memoizing this
+    // try to intelligently serialize property value
+    final propValue = new PropertyPath(path).getValueFrom(this);
+    final serializedValue = serializeValue(propValue);
+    // boolean properties must reflect as boolean attributes
+    if (serializedValue != null) {
+      attributes[path] = serializedValue;
+      // TODO(sorvell): we should remove attr for all properties
+      // that have undefined serialization; however, we will need to
+      // refine the attr reflection system to achieve this; pica, for example,
+      // relies on having inferredType object properties not removed as
+      // attrs.
+    } else if (propValue is bool) {
+      attributes.remove(path);
+    }
+  }
+
+  /// Creates the document fragment to use for each instance of the custom
+  /// element, given the `<template>` node. By default this is equivalent to:
+  ///
+  ///     templateBind(template).createInstance(this, polymerSyntax);
+  ///
+  /// Where polymerSyntax is a singleton [PolymerExpressions] instance.
+  ///
+  /// You can override this method to change the instantiation behavior of the
+  /// template, for example to use a different data-binding syntax.
+  DocumentFragment instanceTemplate(Element template) {
+    // ensure template is decorated (lets things like <tr template ...> work)
+    TemplateBindExtension.decorate(template);
+    var syntax = this.syntax;
+    var t = templateBind(template);
+    if (syntax == null && t.bindingDelegate == null) {
+      syntax = element.syntax;
+    }
+    var dom = t.createInstance(this, syntax);
+    _observers.addAll(getTemplateInstanceBindings(dom));
+    return dom;
+  }
+
+  /// Called by TemplateBinding/NodeBind to setup a binding to the given
+  /// property. It's overridden here to support property bindings in addition to
+  /// attribute bindings that are supported by default.
+  Bindable bind(String name, bindable, {bool oneTime: false}) {
+    var decl = propertyForAttribute(name);
+    if (decl == null) {
+      // Cannot call super.bind because template_binding is its own package
+      return nodeBindFallback(this).bind(name, bindable, oneTime: oneTime);
+    } else {
+      // use n-way Polymer binding
+      var observer = bindProperty(decl.name, bindable, oneTime: oneTime);
+      // NOTE: reflecting binding information is typically required only for
+      // tooling. It has a performance cost so it's opt-in in Node.bind.
+      if (enableBindingsReflection && observer != null) {
+         // Dart note: this is not needed because of how _PolymerBinding works.
+         //observer.path = bindable.path_;
+         _recordBinding(name, observer);
+      }
+      var reflect = _element._reflect;
+
+      // Get back to the (possibly camel-case) name for the property.
+      var propName = smoke.symbolToName(decl.name);
+      if (reflect != null && reflect.contains(propName)) {
+        reflectPropertyToAttribute(propName);
+      }
+      return observer;
+    }
+  }
+
+  _recordBinding(String name, observer) {
+    if (bindings == null) bindings = {};
+    this.bindings[name] = observer;
+  }
+
+  /// Called by TemplateBinding when all bindings on an element have been
+  /// executed. This signals that all element inputs have been gathered and it's
+  /// safe to ready the element, create shadow-root and start data-observation.
+  bindFinished() => _makeElementReady();
+
+  Map<String, Bindable> get bindings => nodeBindFallback(this).bindings;
+  set bindings(Map value) { nodeBindFallback(this).bindings = value; }
+
+  TemplateInstance get templateInstance =>
+      nodeBindFallback(this).templateInstance;
+
+  /// Called at detached time to signal that an element's bindings should be
+  /// cleaned up. This is done asynchronously so that users have the chance to
+  /// call `cancelUnbindAll` to prevent unbinding.
+  void asyncUnbindAll() {
+    if (_unbound == true) return;
+    _unbindLog.fine(() => '[$_name] asyncUnbindAll');
+    _unbindAllJob = scheduleJob(_unbindAllJob, unbindAll);
+  }
+
+  /// This method should rarely be used and only if `cancelUnbindAll` has been
+  /// called to prevent element unbinding. In this case, the element's bindings
+  /// will not be automatically cleaned up and it cannot be garbage collected by
+  /// by the system. If memory pressure is a concern or a large amount of
+  /// elements need to be managed in this way, `unbindAll` can be called to
+  /// deactivate the element's bindings and allow its memory to be reclaimed.
+  void unbindAll() {
+    if (_unbound == true) return;
+    closeObservers();
+    closeNamedObservers();
+    _unbound = true;
+  }
+
+  //// Call in `detached` to prevent the element from unbinding when it is
+  //// detached from the dom. The element is unbound as a cleanup step that
+  //// allows its memory to be reclaimed. If `cancelUnbindAll` is used, consider
+  /// calling `unbindAll` when the element is no longer needed. This will allow
+  /// its memory to be reclaimed.
+  void cancelUnbindAll() {
+    if (_unbound == true) {
+      _unbindLog.warning(() =>
+          '[$_name] already unbound, cannot cancel unbindAll');
+      return;
+    }
+    _unbindLog.fine(() => '[$_name] cancelUnbindAll');
+    if (_unbindAllJob != null) {
+      _unbindAllJob.stop();
+      _unbindAllJob = null;
+    }
+  }
+
+  static void _forNodeTree(Node node, void callback(Node node)) {
+    if (node == null) return;
+
+    callback(node);
+    for (var child = node.firstChild; child != null; child = child.nextNode) {
+      _forNodeTree(child, callback);
+    }
+  }
+
+  /// Creates a CompoundObserver to observe property changes.
+  /// NOTE, this is only done if there are any properties in the `_observe`
+  /// object.
+  void createPropertyObserver() {
+    final observe = _element._observe;
+    if (observe != null) {
+      var o = _propertyObserver = new CompoundObserver();
+      // keep track of property observer so we can shut it down
+      _observers.add(o);
+
+      for (var path in observe.keys) {
+        o.addPath(this, path);
+
+        // TODO(jmesserly): on the Polymer side it doesn't look like they
+        // will observe arrays unless it is a length == 1 path.
+        observeArrayValue(path, path.getValueFrom(this), null);
+      }
+    }
+  }
+
+  /// Start observing property changes.
+  void openPropertyObserver() {
+    if (_propertyObserver != null) {
+      _propertyObserver.open(notifyPropertyChanges);
+    }
+
+    // Dart note: we need an extra listener only to continue supporting
+    // @published properties that follow the old syntax until we get rid of it.
+    // This workaround has timing issues so we prefer the new, not so nice,
+    // syntax.
+    if (_element._publish != null) {
+      changes.listen(_propertyChangeWorkaround);
+    }
+  }
+
+  /// Handler for property changes; routes changes to observing methods.
+  /// Note: array valued properties are observed for array splices.
+  void notifyPropertyChanges(List newValues, Map oldValues, List paths) {
+    final observe = _element._observe;
+    final called = new HashSet();
+
+    oldValues.forEach((i, oldValue) {
+      final newValue = newValues[i];
+
+      // Date note: we don't need any special checking for null and undefined.
+
+      // note: paths is of form [object, path, object, path]
+      final path = paths[2 * i + 1];
+      if (observe == null) return;
+
+      var methods = observe[path];
+      if (methods == null) return;
+
+      for (var method in methods) {
+        if (!called.add(method)) continue; // don't invoke more than once.
+
+        observeArrayValue(path, newValue, oldValue);
+        // Dart note: JS passes "arguments", so we pass along our args.
+        // TODO(sorvell): call method with the set of values it's expecting;
+        // e.g. 'foo bar': 'invalidate' expects the new and old values for
+        // foo and bar. Currently we give only one of these and then
+        // deliver all the arguments.
+        smoke.invoke(this, method,
+            [oldValue, newValue, newValues, oldValues, paths], adjust: true);
+      }
+    });
+  }
+
+  /// Force any pending property changes to synchronously deliver to handlers
+  /// specified in the `observe` object.
+  /// Note: normally changes are processed at microtask time.
+  ///
+  // Dart note: had to rename this to avoid colliding with
+  // Observable.deliverChanges. Even worse, super calls aren't possible or
+  // it prevents Polymer from being a mixin, so we can't override it even if
+  // we wanted to.
+  void deliverPropertyChanges() {
+    if (_propertyObserver != null) {
+      _propertyObserver.deliver();
+    }
+  }
+
+  // Dart note: this workaround is only for old-style @published properties,
+  // which have timing issues. See _bindOldStylePublishedProperty below.
+  // TODO(sigmund): deprecate this.
+  void _propertyChangeWorkaround(List<ChangeRecord> records) {
+    for (var record in records) {
+      if (record is! PropertyChangeRecord) continue;
+
+      var name = record.name;
+      // The setter of a new-style property will create an accessor in
+      // _properties[name]. We can skip the workaround for those properties.
+      if (_properties[name] != null) continue;
+      _propertyChange(name, record.newValue, record.oldValue);
+    }
+  }
+
+  void _propertyChange(Symbol nameSymbol, newValue, oldValue) {
+    _watchLog.info(
+        () => '[$this]: $nameSymbol changed from: $oldValue to: $newValue');
+    var name = smoke.symbolToName(nameSymbol);
+    var reflect = _element._reflect;
+    if (reflect != null && reflect.contains(name)) {
+      reflectPropertyToAttribute(name);
+    }
+  }
+
+  void observeArrayValue(PropertyPath name, Object value, Object old) {
+    final observe = _element._observe;
+    if (observe == null) return;
+
+    // we only care if there are registered side-effects
+    var callbacks = observe[name];
+    if (callbacks == null) return;
+
+    // if we are observing the previous value, stop
+    if (old is ObservableList) {
+      _observeLog.fine(() => '[$_name] observeArrayValue: unregister $name');
+
+      closeNamedObserver('${name}__array');
+    }
+    // if the new value is an array, begin observing it
+    if (value is ObservableList) {
+      _observeLog.fine(() => '[$_name] observeArrayValue: register $name');
+      var sub = value.listChanges.listen((changes) {
+        for (var callback in callbacks) {
+          smoke.invoke(this, callback, [changes], adjust: true);
+        }
+      });
+      registerNamedObserver('${name}__array', sub);
+    }
+  }
+
+  emitPropertyChangeRecord(Symbol name, newValue, oldValue) {
+    if (identical(oldValue, newValue)) return;
+    _propertyChange(name, newValue, oldValue);
+  }
+
+  bindToAccessor(Symbol name, Bindable bindable, {resolveBindingValue: false}) {
+    // Dart note: our pattern is to declare the initial value in the getter.  We
+    // read it via smoke to ensure that the value is initialized correctly.
+    var oldValue = smoke.read(this, name);
+    var property = _properties[name];
+    if (property == null) {
+      // We know that _properties[name] is null only for old-style @published
+      // properties. This fallback is here to make it easier to deprecate the
+      // old-style of published properties, which have bad timing guarantees
+      // (see comment in _PolymerBinding).
+      return _bindOldStylePublishedProperty(name, bindable, oldValue);
+    }
+
+    property.bindable = bindable;
+    var value = bindable.open(property.updateValue);
+
+    if (resolveBindingValue) {
+      // capture A's value if B's value is null or undefined,
+      // otherwise use B's value
+      var v = (value == null ? oldValue : value);
+      if (!identical(value, oldValue)) {
+        bindable.value = value = v;
+      }
+    }
+
+    property.updateValue(value);
+    var o = new _CloseOnlyBinding(property);
+    _observers.add(o);
+    return o;
+  }
+
+  // Dart note: this fallback uses our old-style binding mechanism to be able to
+  // link @published properties with bindings. This mechanism is backwards from
+  // what Javascript does because we can't override the original property. This
+  // workaround also brings some timing issues which are described in detail in
+  // dartbug.com/18343.
+  // TODO(sigmund): deprecate old-style @published properties.
+  _bindOldStylePublishedProperty(Symbol name, Bindable bindable, oldValue) {
+    // capture A's value if B's value is null or undefined,
+    // otherwise use B's value
+    if (bindable.value == null) bindable.value = oldValue;
+
+    var o = new _PolymerBinding(this, name, bindable);
+    _observers.add(o);
+    return o;
+  }
+
+  _getBindingForComputedProperty(Symbol name) {
+    var exprString = element._computed[name];
+    if (exprString == null) return null;
+    var expr = PolymerExpressions.getExpression(exprString);
+    return PolymerExpressions.getBinding(expr, this,
+        globals: element.syntax.globals);
+  }
+
+  createComputedProperties() {
+    var computed = this.element._computed;
+    for (var name in computed.keys) {
+      try {
+        // Dart note: this is done in Javascript by modifying the prototype in
+        // declaration/properties.js, we can't do that, so we do it here.
+        var binding = _getBindingForComputedProperty(name);
+
+        // Follow up note: ideally we would only create the accessor object
+        // here, but some computed properties might depend on others and
+        // evaluating `binding.value` could try to read the value of another
+        // computed property that we haven't created yet. For this reason we
+        // also allow to also create the accessor in [readValue].
+        if (_properties[name] == null) {
+          _properties[name] = new _PropertyAccessor(name, this, binding.value);
+        }
+        bindToAccessor(name, binding);
+      } catch (e) {
+        window.console.error('Failed to create computed property $name'
+            ' (${computed[name]}): $e');
+      }
+    }
+  }
+
+  // Dart note: to simplify the code above we made registerObserver calls
+  // directly invoke _observers.add/addAll.
+  void closeObservers() {
+    for (var o in _observers) {
+      if (o != null) o.close();
+    }
+    _observers = [];
+  }
+
+  /// Bookkeeping observers for memory management.
+  void registerNamedObserver(String name, StreamSubscription sub) {
+    if (_namedObservers == null) {
+      _namedObservers = new Map<String, StreamSubscription>();
+    }
+    _namedObservers[name] = sub;
+  }
+
+  bool closeNamedObserver(String name) {
+    var sub = _namedObservers.remove(name);
+    if (sub == null) return false;
+    sub.cancel();
+    return true;
+  }
+
+  void closeNamedObservers() {
+    if (_namedObservers == null) return;
+    for (var sub in _namedObservers.values) {
+      if (sub != null) sub.cancel();
+    }
+    _namedObservers.clear();
+    _namedObservers = null;
+  }
+
+  /// Bind the [name] property in this element to [bindable]. *Note* in Dart it
+  /// is necessary to also define the field:
+  ///
+  ///     var myProperty;
+  ///
+  ///     ready() {
+  ///       super.ready();
+  ///       bindProperty(#myProperty,
+  ///           new PathObserver(this, 'myModel.path.to.otherProp'));
+  ///     }
+  Bindable bindProperty(Symbol name, bindableOrValue, {oneTime: false}) {
+    // Dart note: normally we only reach this code when we know it's a
+    // property, but if someone uses bindProperty directly they might get a
+    // NoSuchMethodError either from the getField below, or from the setField
+    // inside PolymerBinding. That doesn't seem unreasonable, but it's a slight
+    // difference from Polymer.js behavior.
+
+    _bindLog.fine(() => 'bindProperty: [$bindableOrValue] to [$_name].[$name]');
+
+    if (oneTime) {
+      if (bindableOrValue is Bindable) {
+        _bindLog.warning(() =>
+            'bindProperty: expected non-bindable value n a one-time binding to '
+            '[$_name].[$name], but found $bindableOrValue.');
+      }
+      smoke.write(this, name, bindableOrValue);
+      return null;
+    }
+
+    return bindToAccessor(name, bindableOrValue, resolveBindingValue: true);
+  }
+
+  /// Attach event listeners on the host (this) element.
+  void addHostListeners() {
+    var events = _element._eventDelegates;
+    if (events.isEmpty) return;
+
+    _eventsLog.fine(() => '[$_name] addHostListeners: $events');
+
+    // NOTE: host events look like bindings but really are not;
+    // (1) we don't want the attribute to be set and (2) we want to support
+    // multiple event listeners ('host' and 'instance') and Node.bind
+    // by default supports 1 thing being bound.
+    events.forEach((type, methodName) {
+      // Dart note: the getEventHandler method is on our PolymerExpressions.
+      _PolymerGestures.callMethod(
+          'addEventListener',
+          [this, type, Zone.current.bindUnaryCallback(
+              element.syntax.getEventHandler(this, this, methodName))]);
+    });
+  }
+
+  /// Calls [methodOrCallback] with [args] if it is a closure, otherwise, treat
+  /// it as a method name in [object], and invoke it.
+  void dispatchMethod(object, callbackOrMethod, List args) {
+    _eventsLog.info(() => '>>> [$_name]: dispatch $callbackOrMethod');
+
+    if (callbackOrMethod is Function) {
+      int maxArgs = smoke.maxArgs(callbackOrMethod);
+      if (maxArgs == -1) {
+        _eventsLog.warning(
+            'invalid callback: expected callback of 0, 1, 2, or 3 arguments');
+      }
+      args.length = maxArgs;
+      Function.apply(callbackOrMethod, args);
+    } else if (callbackOrMethod is String) {
+      smoke.invoke(object, smoke.nameToSymbol(callbackOrMethod), args,
+          adjust: true);
+    } else {
+      _eventsLog.warning('invalid callback');
+    }
+
+    _eventsLog.fine(() => '<<< [$_name]: dispatch $callbackOrMethod');
+  }
+
+  /// Call [methodName] method on this object with [args].
+  invokeMethod(Symbol methodName, List args) =>
+      smoke.invoke(this, methodName, args, adjust: true);
+
+  /// Invokes a function asynchronously.
+  /// This will call `Polymer.flush()` and then return a `new Timer`
+  /// with the provided [method] and [timeout].
+  ///
+  /// If you would prefer to run the callback using
+  /// [window.requestAnimationFrame], see the [async] method.
+  ///
+  /// To cancel, call [Timer.cancel] on the result of this method.
+  Timer asyncTimer(void method(), Duration timeout) {
+    // Dart note: "async" is split into 2 methods so it can have a sensible type
+    // signatures. Also removed the various features that don't make sense in a
+    // Dart world, like binding to "this" and taking arguments list.
+
+    // when polyfilling Object.observe, ensure changes
+    // propagate before executing the async method
+    scheduleMicrotask(Observable.dirtyCheck);
+    _Polymer.callMethod('flush'); // for polymer-js interop
+    return new Timer(timeout, method);
+  }
+
+  /// Invokes a function asynchronously. The context of the callback function is
+  /// function is bound to 'this' automatically. Returns a handle which may be
+  /// passed to cancelAsync to cancel the asynchronous call.
+  ///
+  /// If you would prefer to run the callback after a given duration, see
+  /// the [asyncTimer] method.
+  ///
+  /// If you would like to cancel this, use [cancelAsync].
+  int async(RequestAnimationFrameCallback method) {
+    // when polyfilling Object.observe, ensure changes
+    // propagate before executing the async method
+    scheduleMicrotask(Observable.dirtyCheck);
+    _Polymer.callMethod('flush'); // for polymer-js interop
+    return window.requestAnimationFrame(method);
+  }
+
+  /// Cancel an operation scheduled by [async].
+  void cancelAsync(int id) => window.cancelAnimationFrame(id);
+
+  /// Fire a [CustomEvent] targeting [onNode], or `this` if onNode is not
+  /// supplied. Returns the new event.
+  CustomEvent fire(String type, {Object detail, Node onNode, bool canBubble,
+        bool cancelable}) {
+    var node = onNode != null ? onNode : this;
+    var event = new CustomEvent(
+      type,
+      canBubble: canBubble != null ? canBubble : true,
+      cancelable: cancelable != null ? cancelable : true,
+      detail: detail
+    );
+    node.dispatchEvent(event);
+    return event;
+  }
+
+  /// Fire an event asynchronously. See [async] and [fire].
+  asyncFire(String type, {Object detail, Node toNode, bool canBubble}) {
+    // TODO(jmesserly): I'm not sure this method adds much in Dart, it's easy to
+    // add "() =>"
+    async((x) => fire(
+        type, detail: detail, onNode: toNode, canBubble: canBubble));
+  }
+
+  /// Remove [className] from [old], add class to [anew], if they exist.
+  void classFollows(Element anew, Element old, String className) {
+    if (old != null) {
+      old.classes.remove(className);
+    }
+    if (anew != null) {
+      anew.classes.add(className);
+    }
+  }
+
+  /// Installs external stylesheets and <style> elements with the attribute
+  /// polymer-scope='controller' into the scope of element. This is intended
+  /// to be called during custom element construction.
+  void installControllerStyles() {
+    var scope = findStyleScope();
+    if (scope != null && !scopeHasNamedStyle(scope, localName)) {
+      // allow inherited controller styles
+      var decl = _element;
+      var cssText = new StringBuffer();
+      while (decl != null) {
+        cssText.write(decl.cssTextForScope(_STYLE_CONTROLLER_SCOPE));
+        decl = decl.superDeclaration;
+      }
+      if (cssText.isNotEmpty) {
+        installScopeCssText('$cssText', scope);
+      }
+    }
+  }
+
+  void installScopeStyle(style, [String name, Node scope]) {
+    if (scope == null) scope = findStyleScope();
+    if (name == null) name = '';
+
+    if (scope != null && !scopeHasNamedStyle(scope, '$_name$name')) {
+      var cssText = new StringBuffer();
+      if (style is Iterable) {
+        for (var s in style) {
+          cssText..writeln(s.text)..writeln();
+        }
+      } else {
+        cssText = (style as Node).text;
+      }
+      installScopeCssText('$cssText', scope, name);
+    }
+  }
+
+  void installScopeCssText(String cssText, [Node scope, String name]) {
+    if (scope == null) scope = findStyleScope();
+    if (name == null) name = '';
+
+    if (scope == null) return;
+
+    if (_hasShadowDomPolyfill) {
+      cssText = _shimCssText(cssText, scope is ShadowRoot ? scope.host : null);
+    }
+    var style = element.cssTextToScopeStyle(cssText,
+        _STYLE_CONTROLLER_SCOPE);
+    applyStyleToScope(style, scope);
+    // cache that this style has been applied
+    styleCacheForScope(scope).add('$_name$name');
+  }
+
+  Node findStyleScope([node]) {
+    // find the shadow root that contains this element
+    var n = node;
+    if (n == null) n = this;
+    while (n.parentNode != null) {
+      n = n.parentNode;
+    }
+    return n;
+  }
+
+  bool scopeHasNamedStyle(Node scope, String name) =>
+      styleCacheForScope(scope).contains(name);
+
+  Map _polyfillScopeStyleCache = {};
+
+  Set styleCacheForScope(Node scope) {
+    var styles;
+    if (_hasShadowDomPolyfill) {
+      var name = scope is ShadowRoot ? scope.host.localName
+          : (scope as Element).localName;
+      var styles = _polyfillScopeStyleCache[name];
+      if (styles == null) _polyfillScopeStyleCache[name] = styles = new Set();
+    } else {
+      styles = _scopeStyles[scope];
+      if (styles == null) _scopeStyles[scope] = styles = new Set();
+    }
+    return styles;
+  }
+
+  static final _scopeStyles = new Expando();
+
+  static String _shimCssText(String cssText, [Element host]) {
+    var name = '';
+    var is_ = false;
+    if (host != null) {
+      name = host.localName;
+      is_ = host.attributes.containsKey('is');
+    }
+    var selector = _ShadowCss.callMethod('makeScopeSelector', [name, is_]);
+    return _ShadowCss.callMethod('shimCssText', [cssText, selector]);
+  }
+
+  static void applyStyleToScope(StyleElement style, Node scope) {
+    if (style == null) return;
+
+    if (scope == document) scope = document.head;
+
+    if (_hasShadowDomPolyfill) scope = document.head;
+
+    // TODO(sorvell): necessary for IE
+    // see https://connect.microsoft.com/IE/feedback/details/790212/
+    // cloning-a-style-element-and-adding-to-document-produces
+    // -unexpected-result#details
+    // var clone = style.cloneNode(true);
+    var clone = new StyleElement()..text = style.text;
+
+    var attr = style.attributes[_STYLE_SCOPE_ATTRIBUTE];
+    if (attr != null) {
+      clone.attributes[_STYLE_SCOPE_ATTRIBUTE] = attr;
+    }
+
+    // TODO(sorvell): probably too brittle; try to figure out
+    // where to put the element.
+    var refNode = scope.firstChild;
+    if (scope == document.head) {
+      var selector = 'style[$_STYLE_SCOPE_ATTRIBUTE]';
+      var styleElement = document.head.querySelectorAll(selector);
+      if (styleElement.isNotEmpty) {
+        refNode = styleElement.last.nextElementSibling;
+      }
+    }
+    scope.insertBefore(clone, refNode);
+  }
+
+  /// Invoke [callback] in [wait], unless the job is re-registered,
+  /// which resets the timer. If [wait] is not supplied, this will use
+  /// [window.requestAnimationFrame] instead of a [Timer].
+  ///
+  /// For example:
+  ///
+  ///     _myJob = Polymer.scheduleJob(_myJob, callback);
+  ///
+  /// Returns the newly created job.
+  // Dart note: renamed to scheduleJob to be a bit more consistent with Dart.
+  PolymerJob scheduleJob(PolymerJob job, void callback(), [Duration wait]) {
+    if (job == null) job = new PolymerJob._();
+    // Dart note: made start smarter, so we don't need to call stop.
+    return job..start(callback, wait);
+  }
+
+  /// Inject HTML which contains markup bound to this element into
+  /// a target element (replacing target element content).
+  DocumentFragment injectBoundHTML(String html, [Element element]) {
+    var template = new TemplateElement()..innerHtml = html;
+    var fragment = this.instanceTemplate(template);
+    if (element != null) {
+      element.text = '';
+      element.append(fragment);
+    }
+    return fragment;
+  }
+}
+
+// Dart note: this is related to _bindOldStylePublishedProperty. Polymer
+// addresses n-way bindings by metaprogramming: redefine the property on the
+// PolymerElement instance to always get its value from the model@path. This is
+// supported in Dart using a new style of @published property declaration using
+// the `readValue` and `writeValue` methods above. In the past we used to work
+// around this by listening to changes on both sides and updating the values.
+// This object provides the hooks to do this.
+// TODO(sigmund,jmesserly): delete after a deprecation period.
+class _PolymerBinding extends Bindable {
+  final Polymer _target;
+  final Symbol _property;
+  final Bindable _bindable;
+  StreamSubscription _sub;
+  Object _lastValue;
+
+  _PolymerBinding(this._target, this._property, this._bindable) {
+    _sub = _target.changes.listen(_propertyValueChanged);
+    _updateNode(open(_updateNode));
+  }
+
+  void _updateNode(newValue) {
+    _lastValue = newValue;
+    smoke.write(_target, _property, newValue);
+    // Note: we don't invoke emitPropertyChangeRecord here because that's
+    // done by listening on changes on the PolymerElement.
+  }
+
+  void _propertyValueChanged(List<ChangeRecord> records) {
+    for (var record in records) {
+      if (record is PropertyChangeRecord && record.name == _property) {
+        final newValue = smoke.read(_target, _property);
+        if (!identical(_lastValue, newValue)) {
+          this.value = newValue;
+        }
+        return;
+      }
+    }
+  }
+
+  open(callback(value)) => _bindable.open(callback);
+  get value => _bindable.value;
+  set value(newValue) => _bindable.value = newValue;
+
+  void close() {
+    if (_sub != null) {
+      _sub.cancel();
+      _sub = null;
+    }
+    _bindable.close();
+  }
+}
+
+// Ported from an inline object in instance/properties.js#bindToAccessor.
+class _CloseOnlyBinding extends Bindable {
+  final _PropertyAccessor accessor;
+
+  _CloseOnlyBinding(this.accessor);
+
+  open(callback) {}
+  get value => null;
+  set value(newValue) {}
+  deliver() {}
+
+  void close() {
+    if (accessor.bindable == null) return;
+    accessor.bindable.close();
+    accessor.bindable = null;
+  }
+}
+
+bool _toBoolean(value) => null != value && false != value;
+
+final Logger _observeLog = new Logger('polymer.observe');
+final Logger _eventsLog = new Logger('polymer.events');
+final Logger _unbindLog = new Logger('polymer.unbind');
+final Logger _bindLog = new Logger('polymer.bind');
+final Logger _watchLog = new Logger('polymer.watch');
+final Logger _readyLog = new Logger('polymer.ready');
+
+final Expando _eventHandledTable = new Expando<Set<Node>>();
+
+final JsObject _PolymerGestures = js.context['PolymerGestures'];
+