Adding Angular and dependent packages for testing

third_party/pkg/angular/lib/core/scope.dart

Index: third_party/pkg/angular/lib/core/scope.dart
diff --git a/third_party/pkg/angular/lib/core/scope.dart b/third_party/pkg/angular/lib/core/scope.dart
new file mode 100644
index 0000000000000000000000000000000000000000..72637b8bf25d16e7127997a7de726ccb6fcd3678
--- /dev/null
+++ b/third_party/pkg/angular/lib/core/scope.dart
@@ -0,0 +1,882 @@
+part of angular.core;
+
+
+/**
+ * Used by [Scope.$on] to notify the listeners of events.
+ */
+class ScopeEvent {
+  String name;
+  Scope targetScope;
+  Scope currentScope;
+  bool propagationStopped = false;
+  bool defaultPrevented = false;
+
+  ScopeEvent(this.name, this.targetScope);
+
+  stopPropagation () => propagationStopped = true;
+  preventDefault() => defaultPrevented = true;
+}
+
+/**
+ * Allows the configuration of [Scope.$digest] iteration maximum time-to-live
+ * value. Digest keeps checking the state of the watcher getters until it
+ * can execute one full iteration with no watchers triggering. TTL is used
+ * to prevent an infinite loop where watch A triggers watch B which in turn
+ * triggers watch A. If the system does not stabilize in TTL iteration then
+ * an digest is stop an an exception is thrown.
+ */
+@NgInjectableService()
+class ScopeDigestTTL {
+  final num ttl;
+  ScopeDigestTTL(): ttl = 5;
+  ScopeDigestTTL.value(num this.ttl);
+}
+
+/**
+ * Scope has two responsibilities. 1) to keep track af watches and 2)
+ * to keep references to the model so that they are available for
+ * data-binding.
+ */
+@proxy
+@NgInjectableService()
+class Scope implements Map {
+  final ExceptionHandler _exceptionHandler;
+  final Parser _parser;
+  final NgZone _zone;
+  final num _ttl;
+  final Map<String, Object> _properties = {};
+  final _WatchList _watchers = new _WatchList();
+  final Map<String, List<Function>> _listeners = {};
+  final bool _isolate;
+  final bool _lazy;
+  final Profiler _perf;
+  final Scope $parent;
+
+  String $id;
+  Scope $root;
+  num _nextId = 0;
+  String _phase;
+  List _innerAsyncQueue;
+  List _outerAsyncQueue;
+  Scope _nextSibling, _prevSibling, _childHead, _childTail;
+  bool _skipAutoDigest = false;
+  bool _disabled = false;
+
+  Scope(this._exceptionHandler, this._parser, ScopeDigestTTL ttl,
+      this._zone, this._perf):
+        $parent = null, _isolate = false, _lazy = false, _ttl = ttl.ttl {
+    _properties[r'this']= this;
+    $root = this;
+    $id = '_${$root._nextId++}';
+    _innerAsyncQueue = [];
+    _outerAsyncQueue = [];
+
+    // Set up the zone to auto digest this scope.
+    _zone.onTurnDone = _autoDigestOnTurnDone;
+    _zone.onError = (e, s, ls) => _exceptionHandler(e, s);
+  }
+
+  Scope._child(Scope parent, bool this._isolate, bool this._lazy, Profiler this._perf):
+      $parent = parent, _ttl = parent._ttl, _parser = parent._parser,
+      _exceptionHandler = parent._exceptionHandler, _zone = parent._zone {
+    _properties[r'this'] = this;
+    $root = $parent.$root;
+    $id = '_${$root._nextId++}';
+    _innerAsyncQueue = $parent._innerAsyncQueue;
+    _outerAsyncQueue = $parent._outerAsyncQueue;
+
+    _prevSibling = $parent._childTail;
+    if ($parent._childHead != null) {
+      $parent._childTail._nextSibling = this;
+      $parent._childTail = this;
+    } else {
+      $parent._childHead = $parent._childTail = this;
+    }
+  }
+
+  _autoDigestOnTurnDone() {
+    if (_skipAutoDigest) {
+      _skipAutoDigest = false;
+    } else {
+      $digest();
+    }
+  }
+
+  _identical(a, b) =>
+    identical(a, b) ||
+    (a is String && b is String && a == b) ||
+    (a is num && b is num && a.isNaN && b.isNaN);
+
+  containsKey(String name) => this[name] != null;
+  remove(String name) => this._properties.remove(name);
+  operator []=(String name, value) => _properties[name] = value;
+  operator [](String name) {
+    if (name == r'$id') return this.$id;
+    if (name == r'$parent') return this.$parent;
+    if (name == r'$root') return this.$root;
+    var scope = this;
+    do {
+      if (scope._properties.containsKey(name)) {
+        return scope._properties[name];
+      } else if (!scope._isolate) {
+        scope = scope.$parent;
+      } else {
+        return null;
+      }
+    } while(scope != null);
+    return null;
+  }
+
+  noSuchMethod(Invocation invocation) {
+    var name = MirrorSystem.getName(invocation.memberName);
+    if (invocation.isGetter) {
+      return this[name];
+    } else if (invocation.isSetter) {
+      var value = invocation.positionalArguments[0];
+      name = name.substring(0, name.length - 1);
+      this[name] = value;
+      return value;
+    } else {
+      if (this[name] is Function) {
+        return this[name]();
+      } else {
+        super.noSuchMethod(invocation);
+      }
+    }
+  }
+
+
+  /**
+   * Create a new child [Scope].
+   *
+   * * [isolate] - If set to true the child scope does not inherit properties from the parent scope.
+   *   This in essence creates an independent (isolated) view for the users of the scope.
+   * * [lazy] - If set to true the scope digest will only run if the scope is marked as [$dirty].
+   *   This is usefull if we expect that the bindings in the scope are constant and there is no need
+   *   to check them on each digest. The digest can be forced by marking it [$dirty].
+   */
+  $new({bool isolate: false, bool lazy: false}) =>
+    new Scope._child(this, isolate, lazy, _perf);
+
+  /**
+   * *EXPERIMENTAL:* This feature is experimental. We reserve the right to change or delete it.
+   *
+   * A dissabled scope will not be part of the [$digest] cycle until it is re-enabled.
+   */
+  set $disabled(value) => this._disabled = value;
+  get $disabled => this._disabled;
+
+  /**
+   * Registers a listener callback to be executed whenever the [watchExpression] changes.
+   *
+   * The watchExpression is called on every call to [$digest] and should return the value that
+   * will be watched. (Since [$digest] reruns when it detects changes the watchExpression can
+   * execute multiple times per [$digest] and should be idempotent.)
+   *
+   * The listener is called only when the value from the current [watchExpression] and the
+   * previous call to [watchExpression] are not identical (with the exception of the initial run,
+   * see below).
+   *
+   * The watch listener may change the model, which may trigger other listeners to fire. This is
+   * achieved by rerunning the watchers until no changes are detected. The rerun iteration limit
+   * is 10 to prevent an infinite loop deadlock.
+   * If you want to be notified whenever [$digest] is called, you can register a [watchExpression]
+   * function with no listener. (Since [watchExpression] can execute multiple times per [$digest]
+   * cycle when a change is detected, be prepared for multiple calls to your listener.)
+   *
+   * After a watcher is registered with the scope, the listener fn is called asynchronously
+   * (via [$evalAsync]) to initialize the watcher. In rare cases, this is undesirable because the
+   * listener is called when the result of [watchExpression] didn't change. To detect this
+   * scenario within the listener fn, you can compare the newVal and oldVal. If these two values
+   * are identical then the listener was called due to initialization.
+   *
+   * * [watchExpression] - can be any one of these: a [Function] - `(Scope scope) => ...;` or a
+   *   [String]  - `expression` which is compiled with [Parser] service into a function
+   * * [listener] - A [Function] `(currentValue, previousValue, Scope scope) => ...;`
+   * * [watchStr] - Used as a debbuging hint to easier identify which expression is associated with
+   *   this watcher.
+   */
+  $watch(watchExpression, [Function listener, String watchStr]) {
+    if (watchStr == null) {
+      watchStr = watchExpression.toString();
+
+      // Keep prod fast
+      assert((() {
+        watchStr = _source(watchExpression);
+        return true;
+      })());
+    }
+    var watcher = new _Watch(_compileToFn(listener), _initWatchVal,
+        _compileToFn(watchExpression), watchStr);
+    _watchers.addLast(watcher);
+    return () => _watchers.remove(watcher);
+  }
+
+  /**
+   * A variant of [$watch] where it watches a collection of [watchExpressios]. If any
+   * one expression in the collection changes the [listener] is executed.
+   *
+   * * [watcherExpressions] - `List<String|(Scope scope){}>`
+   * * [Listener] - `(List newValues, List previousValues, Scope scope)`
+   */
+  $watchSet(List watchExpressions, [Function listener, String watchStr]) {
+    if (watchExpressions.length == 0) return () => null;
+
+    var lastValues = new List(watchExpressions.length);
+    var currentValues = new List(watchExpressions.length);
+
+    if (watchExpressions.length == 1) {
+    // Special case size of one.
+      return $watch(watchExpressions[0], (value, oldValue, scope) {
+        currentValues[0] = value;
+        lastValues[0] = oldValue;
+        listener(currentValues, lastValues, scope);
+      });
+    }
+    var deregesterFns = [];
+    var changeCount = 0;
+    for(var i = 0, ii = watchExpressions.length; i < ii; i++) {
+      deregesterFns.add($watch(watchExpressions[i], (value, oldValue, __) {
+        currentValues[i] = value;
+        lastValues[i] = oldValue;
+        changeCount++;
+      }));
+    }
+    deregesterFns.add($watch((s) => changeCount, (c, o, scope) {
+      listener(currentValues, lastValues, scope);
+    }));
+    return () {
+      for(var i = 0, ii = deregesterFns.length; i < ii; i++) {
+        deregesterFns[i]();
+      }
+    };
+  }
+
+  /**
+   * Shallow watches the properties of an object and fires whenever any of the properties change
+   * (for arrays, this implies watching the array items; for object maps, this implies watching
+   * the properties). If a change is detected, the listener callback is fired.
+   *
+   *  The obj collection is observed via standard [$watch] operation and is examined on every call
+   *  to [$digest] to see if any items have been added, removed, or moved.
+   *
+   *  The listener is called whenever anything within the obj has changed. Examples include
+   *  adding, removing, and moving items belonging to an object or array.
+   */
+  $watchCollection(obj, listener, [String expression, bool shallow=false]) {
+    var oldValue;
+    var newValue;
+    int changeDetected = 0;
+    Function objGetter = _compileToFn(obj);
+    List internalArray = [];
+    Map internalMap = {};
+    int oldLength = 0;
+    int newLength;
+    var key;
+    List keysToRemove = [];
+    Function detectNewKeys = (key, value) {
+      newLength++;
+      if (oldValue.containsKey(key)) {
+        if (!_identical(oldValue[key], value)) {
+          changeDetected++;
+          oldValue[key] = value;
+        }
+      } else {
+        oldLength++;
+        oldValue[key] = value;
+        changeDetected++;
+      }
+    };
+    Function findMissingKeys = (key, _) {
+      if (!newValue.containsKey(key)) {
+        oldLength--;
+        keysToRemove.add(key);
+      }
+    };
+
+    Function removeMissingKeys = (k) => oldValue.remove(k);
+
+    var $watchCollectionWatch;
+
+    if (shallow) {
+      $watchCollectionWatch = (_) {
+        newValue = objGetter(this);
+        newLength = newValue == null ? 0 : newValue.length;
+        if (newLength != oldLength) {
+          oldLength = newLength;
+          changeDetected++;
+        }
+        if (!identical(oldValue, newValue)) {
+          oldValue = newValue;
+          changeDetected++;
+        }
+        return changeDetected;
+      };
+    } else {
+      $watchCollectionWatch = (_) {
+        newValue = objGetter(this);
+
+        if (newValue is! Map && newValue is! List) {
+          if (!_identical(oldValue, newValue)) {
+            oldValue = newValue;
+            changeDetected++;
+          }
+        } else if (newValue is Iterable) {
+          if (!_identical(oldValue, internalArray)) {
+            // we are transitioning from something which was not an array into array.
+            oldValue = internalArray;
+            oldLength = oldValue.length = 0;
+            changeDetected++;
+          }
+
+          newLength = newValue.length;
+
+          if (oldLength != newLength) {
+            // if lengths do not match we need to trigger change notification
+            changeDetected++;
+            oldValue.length = oldLength = newLength;
+          }
+          // copy the items to oldValue and look for changes.
+          for (var i = 0; i < newLength; i++) {
+            if (!_identical(oldValue[i], newValue.elementAt(i))) {
+              changeDetected++;
+              oldValue[i] = newValue.elementAt(i);
+            }
+          }
+        } else { // Map
+          if (!_identical(oldValue, internalMap)) {
+            // we are transitioning from something which was not an object into object.
+            oldValue = internalMap = {};
+            oldLength = 0;
+            changeDetected++;
+          }
+          // copy the items to oldValue and look for changes.
+          newLength = 0;
+          newValue.forEach(detectNewKeys);
+          if (oldLength > newLength) {
+            // we used to have more keys, need to find them and destroy them.
+            changeDetected++;
+            oldValue.forEach(findMissingKeys);
+            keysToRemove.forEach(removeMissingKeys);
+            keysToRemove.clear();
+          }
+        }
+        return changeDetected;
+      };
+    }
+
+    var $watchCollectionAction = (_, __, ___) {
+      relaxFnApply(listener, [newValue, oldValue, this]);
+    };
+
+    return this.$watch($watchCollectionWatch,
+                       $watchCollectionAction,
+                       expression == null ? obj : expression);
+  }
+
+
+  /**
+   * Add this function to your code if you want to add a $digest
+   * and want to assert that the digest will be called on this turn.
+   * This method will be deleted when we are comfortable with
+   * auto-digesting scope.
+   */
+  $$verifyDigestWillRun() {
+    assert(!_skipAutoDigest);
+    _zone.assertInTurn();
+  }
+
+  /**
+   * *EXPERIMENTAL:* This feature is experimental. We reserve the right to change or delete it.
+   *
+   * Marks a scope as dirty. If the scope is lazy (see [$new]) then the scope will be included
+   * in the next [$digest].
+   *
+   * NOTE: This has no effect for non-lazy scopes.
+   */
+  $dirty() {
+    this._disabled = false;
+  }
+
+  $digest() {
+    try {
+      _beginPhase('\$digest');
+      _digestWhileDirtyLoop();
+    } catch (e, s) {
+      _exceptionHandler(e, s);
+    } finally {
+      _clearPhase();
+    }
+  }
+
+
+  _digestWhileDirtyLoop() {
+    _digestHandleQueue('ng.innerAsync', _innerAsyncQueue);
+
+    int timerId;
+    assert((timerId = _perf.startTimer('ng.dirty_check', 0)) != false);
+    _Watch lastDirtyWatch = _digestComputeLastDirty();
+    assert(_perf.stopTimer(timerId) != false);
+
+    if (lastDirtyWatch == null) {
+      _digestHandleQueue('ng.outerAsync', _outerAsyncQueue);
+      return;
+    }
+
+    List<List<String>> watchLog = [];
+    for (int iteration = 1, ttl = _ttl; iteration < ttl; iteration++) {
+      _Watch stopWatch = _digestHandleQueue('ng.innerAsync', _innerAsyncQueue)
+          ? null  // Evaluating async work requires re-evaluating all watchers.
+          : lastDirtyWatch;
+      lastDirtyWatch = null;
+
+      List<String> expressionLog;
+      if (ttl - iteration <= 3) {
+        expressionLog = <String>[];
+        watchLog.add(expressionLog);
+      }
+
+      int timerId;
+      assert((timerId = _perf.startTimer('ng.dirty_check', iteration)) != false);
+      lastDirtyWatch = _digestComputeLastDirtyUntil(stopWatch, expressionLog);
+      assert(_perf.stopTimer(timerId) != false);
+
+      if (lastDirtyWatch == null) {
+        _digestComputePerfCounters();
+        _digestHandleQueue('ng.outerAsync', _outerAsyncQueue);
+        return;
+      }
+    }
+
+    // I've seen things you people wouldn't believe. Attack ships on fire
+    // off the shoulder of Orion. I've watched C-beams glitter in the dark
+    // near the Tannhauser Gate. All those moments will be lost in time,
+    // like tears in rain. Time to die.
+    throw '$_ttl \$digest() iterations reached. Aborting!\n'
+          'Watchers fired in the last ${watchLog.length} iterations: '
+          '${_toJson(watchLog)}';
+  }
+
+
+  bool _digestHandleQueue(String timerName, List queue) {
+    if (queue.isEmpty) {
+      return false;
+    }
+    do {
+      var timerId;
+      try {
+        var workFn = queue.removeAt(0);
+        assert((timerId = _perf.startTimer(timerName, _source(workFn))) != false);
+        $root.$eval(workFn);
+      } catch (e, s) {
+        _exceptionHandler(e, s);
+      } finally {
+        assert(_perf.stopTimer(timerId) != false);
+      }
+    } while (queue.isNotEmpty);
+    return true;
+  }
+
+
+  _Watch _digestComputeLastDirty() {
+    int watcherCount = 0;
+    int scopeCount = 0;
+    Scope scope = this;
+    do {
+      _WatchList watchers = scope._watchers;
+      watcherCount += watchers.length;
+      scopeCount++;
+      for (_Watch watch = watchers.head; watch != null; watch = watch.next) {
+        var last = watch.last;
+        var value = watch.get(scope);
+        if (!_identical(value, last)) {
+          return _digestHandleDirty(scope, watch, last, value, null);
+        }
+      }
+    } while ((scope = _digestComputeNextScope(scope)) != null);
+    _digestUpdatePerfCounters(watcherCount, scopeCount);
+    return null;
+  }
+
+
+  _Watch _digestComputeLastDirtyUntil(_Watch stopWatch, List<String> log) {
+    int watcherCount = 0;
+    int scopeCount = 0;
+    Scope scope = this;
+    do {
+      _WatchList watchers = scope._watchers;
+      watcherCount += watchers.length;
+      scopeCount++;
+      for (_Watch watch = watchers.head; watch != null; watch = watch.next) {
+        if (identical(stopWatch, watch)) return null;
+        var last = watch.last;
+        var value = watch.get(scope);
+        if (!_identical(value, last)) {
+          return _digestHandleDirty(scope, watch, last, value, log);
+        }
+      }
+    } while ((scope = _digestComputeNextScope(scope)) != null);
+    return null;
+  }
+
+
+  _Watch _digestHandleDirty(Scope scope, _Watch watch, last, value, List<String> log) {
+    _Watch lastDirtyWatch;
+    while (true) {
+      if (!_identical(value, last)) {
+        lastDirtyWatch = watch;
+        if (log != null) log.add(watch.exp == null ? '[unknown]' : watch.exp);
+        watch.last = value;
+        var fireTimer;
+        assert((fireTimer = _perf.startTimer('ng.fire', watch.exp)) != false);
+        watch.fn(value, identical(_initWatchVal, last) ? value : last, scope);
+        assert(_perf.stopTimer(fireTimer) != false);
+      }
+      watch = watch.next;
+      while (watch == null) {
+        scope = _digestComputeNextScope(scope);
+        if (scope == null) return lastDirtyWatch;
+        watch = scope._watchers.head;
+      }
+      last = watch.last;
+      value = watch.get(scope);
+    }
+  }
+
+
+  Scope _digestComputeNextScope(Scope scope) {
+    // Insanity Warning: scope depth-first traversal
+    // yes, this code is a bit crazy, but it works and we have tests to prove it!
+    // this piece should be kept in sync with the traversal in $broadcast
+    Scope target = this;
+    Scope childHead = scope._childHead;
+    while (childHead != null && childHead._disabled) {
+      childHead = childHead._nextSibling;
+    }
+    if (childHead == null) {
+      if (scope == target) {
+        return null;
+      } else {
+        Scope next = scope._nextSibling;
+        if (next == null) {
+          while (scope != target && (next = scope._nextSibling) == null) {
+            scope = scope.$parent;
+          }
+        }
+        return next;
+      }
+    } else {
+      if (childHead._lazy) childHead._disabled = true;
+      return childHead;
+    }
+  }
+
+
+  void _digestComputePerfCounters() {
+    int watcherCount = 0, scopeCount = 0;
+    Scope scope = this;
+    do {
+      scopeCount++;
+      watcherCount += scope._watchers.length;
+    } while ((scope = _digestComputeNextScope(scope)) != null);
+    _digestUpdatePerfCounters(watcherCount, scopeCount);
+  }
+
+
+  void _digestUpdatePerfCounters(int watcherCount, int scopeCount) {
+    _perf.counters['ng.scope.watchers'] = watcherCount;
+    _perf.counters['ng.scopes'] = scopeCount;
+  }
+
+
+  $destroy() {
+    if ($root == this) return; // we can't remove the root node;
+
+    $broadcast(r'$destroy');
+
+    if ($parent._childHead == this) $parent._childHead = _nextSibling;
+    if ($parent._childTail == this) $parent._childTail = _prevSibling;
+    if (_prevSibling != null) _prevSibling._nextSibling = _nextSibling;
+    if (_nextSibling != null) _nextSibling._prevSibling = _prevSibling;
+  }
+
+
+  $eval(expr, [locals]) {
+    return relaxFnArgs(_compileToFn(expr))(locals == null ? this : new ScopeLocals(this, locals));
+  }
+
+
+  $evalAsync(expr, {outsideDigest: false}) {
+    if (outsideDigest) {
+      _outerAsyncQueue.add(expr);
+    } else {
+      _innerAsyncQueue.add(expr);
+    }
+  }
+
+
+  /**
+   * Skip running a $digest at the end of this turn.
+   * The primary use case is to skip the digest in the current VM turn because
+   * you just scheduled or are otherwise certain of an impending VM turn and the
+   * digest at the end of that turn is sufficient.  You should be able to answer
+   * "No" to the question "Is there any other code that is aware that this VM
+   * turn occured and therefore expected a digest?".  If your answer is "Yes",
+   * then you run the risk that the very next VM turn is not for your event and
+   * now that other code runs in that turn and sees stale values.
+   *
+   * You might call this function, for instance, from an event listener where,
+   * though the event occured, you need to wait for another event before you can
+   * perform something meaningful.  You might schedule that other event,
+   * set a flag for the handler of the other event to recognize, etc. and then
+   * call this method to skip the digest this cycle.  Note that you should call
+   * this function *after* you have successfully confirmed that the expected VM
+   * turn will occur (perhaps by scheduling it) to ensure that the digest
+   * actually does take place on that turn.
+   */
+  $skipAutoDigest() {
+    _zone.assertInTurn();
+    _skipAutoDigest = true;
+  }
+
+
+  $apply([expr]) {
+    return _zone.run(() {
+      var timerId;
+      try {
+        assert((timerId = _perf.startTimer('ng.\$apply', _source(expr))) != false);
+        return $eval(expr);
+      } catch (e, s) {
+        _exceptionHandler(e, s);
+      } finally {
+        assert(_perf.stopTimer(timerId) != false);
+      }
+    });
+  }
+
+
+  $on(name, listener) {
+    var namedListeners = _listeners[name];
+    if (!_listeners.containsKey(name)) {
+      _listeners[name] = namedListeners = [];
+    }
+    namedListeners.add(listener);
+
+    return () {
+      namedListeners.remove(listener);
+    };
+  }
+
+
+  $emit(name, [List args]) {
+    var empty = [],
+        namedListeners,
+        scope = this,
+        event = new ScopeEvent(name, this),
+        listenerArgs = [event],
+        i;
+
+    if (args != null) {
+      listenerArgs.addAll(args);
+    }
+
+    do {
+      namedListeners = scope._listeners[name];
+      if (namedListeners != null) {
+        event.currentScope = scope;
+        i = 0;
+        for (var length = namedListeners.length; i<length; i++) {
+          try {
+            relaxFnApply(namedListeners[i], listenerArgs);
+            if (event.propagationStopped) return event;
+          } catch (e, s) {
+            _exceptionHandler(e, s);
+          }
+        }
+      }
+      //traverse upwards
+      scope = scope.$parent;
+    } while (scope != null);
+
+    return event;
+  }
+
+
+  $broadcast(String name, [List listenerArgs]) {
+    var target = this,
+        current = target,
+        next = target,
+        event = new ScopeEvent(name, this);
+
+    //down while you can, then up and next sibling or up and next sibling until back at root
+    if (listenerArgs == null) {
+      listenerArgs = [];
+    }
+    listenerArgs.insert(0, event);
+    do {
+      current = next;
+      event.currentScope = current;
+      if (current._listeners.containsKey(name)) {
+        current._listeners[name].forEach((listener) {
+          try {
+            relaxFnApply(listener, listenerArgs);
+          } catch(e, s) {
+            _exceptionHandler(e, s);
+          }
+        });
+      }
+
+      // Insanity Warning: scope depth-first traversal
+      // yes, this code is a bit crazy, but it works and we have tests to prove it!
+      // this piece should be kept in sync with the traversal in $broadcast
+      if (current._childHead == null) {
+        if (current == target) {
+          next = null;
+        } else {
+          next = current._nextSibling;
+          if (next == null) {
+            while(current != target && (next = current._nextSibling) == null) {
+              current = current.$parent;
+            }
+          }
+        }
+      } else {
+        next = current._childHead;
+      }
+    } while ((current = next) != null);
+
+    return event;
+  }
+
+  _beginPhase(phase) {
+    if ($root._phase != null) {
+      // TODO(deboer): Remove the []s when dartbug.com/11999 is fixed.
+      throw ['${$root._phase} already in progress'];
+    }
+    assert(_perf.startTimer('ng.phase.${phase}') != false);
+
+    $root._phase = phase;
+  }
+
+  _clearPhase() {
+    assert(_perf.stopTimer('ng.phase.${$root._phase}') != false);
+    $root._phase = null;
+  }
+
+  Function _compileToFn(exp) {
+    if (exp == null) {
+      return () => null;
+    } else if (exp is String) {
+      return _parser(exp).eval;
+    } else if (exp is Function) {
+      return exp;
+    } else {
+      throw 'Expecting String or Function';
+    }
+  }
+}
+
+@proxy
+class ScopeLocals implements Scope, Map {
+  static wrapper(dynamic scope, Map<String, Object> locals) => new ScopeLocals(scope, locals);
+
+  dynamic _scope;
+  Map<String, Object> _locals;
+
+  ScopeLocals(this._scope, this._locals);
+
+  operator []=(String name, value) => _scope[name] = value;
+  operator [](String name) => (_locals.containsKey(name) ? _locals : _scope)[name];
+
+  noSuchMethod(Invocation invocation) => mirror.reflect(_scope).delegate(invocation);
+}
+
+class _InitWatchVal { const _InitWatchVal(); }
+const _initWatchVal = const _InitWatchVal();
+
+class _Watch {
+  final Function fn;
+  final Function get;
+  final String exp;
+  var last;
+
+  _Watch previous;
+  _Watch next;
+
+  _Watch(fn, this.last, getFn, this.exp)
+      : this.fn  = relaxFnArgs3(fn)
+      , this.get = relaxFnArgs1(getFn);
+}
+
+class _WatchList {
+  int length = 0;
+  _Watch head;
+  _Watch tail;
+
+  void addLast(_Watch watch) {
+    assert(watch.previous == null);
+    assert(watch.next == null);
+    if (tail == null) {
+      tail = head = watch;
+    } else {
+      watch.previous = tail;
+      tail.next = watch;
+      tail = watch;
+    }
+    length++;
+  }
+
+  void remove(_Watch watch) {
+    if (watch == head) {
+      _Watch next = watch.next;
+      if (next == null) tail = null;
+      else next.previous = null;
+      head = next;
+    } else if (watch == tail) {
+      _Watch previous = watch.previous;
+      previous.next = null;
+      tail = previous;
+    } else {
+      _Watch next = watch.next;
+      _Watch previous = watch.previous;
+      previous.next = next;
+      next.previous = previous;
+    }
+    length--;
+  }
+}
+
+_toJson(obj) {
+  try {
+    return JSON.encode(obj);
+  } catch(e) {
+    var ret = "NOT-JSONABLE";
+    // Keep prod fast.
+    assert((() {
+      var mirror = reflect(obj);
+      if (mirror is ClosureMirror) {
+        // work-around dartbug.com/14130
+        try {
+          ret = mirror.function.source;
+        } on NoSuchMethodError catch (e) {}
+      }
+      return true;
+    })());
+    return ret;
+  }
+}
+
+String _source(obj) {
+  if (obj is Function) {
+    var m = reflect(obj);
+    if (m is ClosureMirror) {
+      // work-around dartbug.com/14130
+      try {
+        return "FN: ${m.function.source}";
+      } on NoSuchMethodError catch (e) {
+      } on UnimplementedError catch (e) {
+      }
+    }
+  }
+  return '$obj';
+}