fix(query): clean-up queryref during dehydration

The QueryRef objects persists during dehydration but needs to be
cleaned-up by removing callbacks and previous elements.

Closes #3944

Closes #3948

modules/angular2/src/core/compiler/element_injector.ts

@@ -433,6 +433,7 @@ export class ElementInjector extends TreeNode<ElementInjector> implements Depend
     this._preBuiltObjects = null;
     this._strategy.callOnDestroy();
     this._strategy.dehydrate();
+    this._clearQueryLists();
   }
 
   afterContentChecked(): void {
@@ -837,6 +838,12 @@ export class ElementInjector extends TreeNode<ElementInjector> implements Depend
     var nestedView = view.getNestedView(view.elementOffset + this.getBoundElementIndex());
     return isPresent(nestedView) ? nestedView.rootElementInjectors : [];
   }
+
+  private _clearQueryLists(): void {
+    if (isPresent(this._query0) && this._query0.originator === this) this._query0.reset();
+    if (isPresent(this._query1) && this._query1.originator === this) this._query1.reset();
+    if (isPresent(this._query2) && this._query2.originator === this) this._query2.reset();
+  }
 }
 
 interface _ElementInjectorStrategy {
@@ -1163,4 +1170,9 @@ export class QueryRef {
   private _aggregateDirective(inj: ElementInjector, aggregator: any[]): void {
     inj.addDirectivesMatchingQuery(this.query, aggregator);
   }
+
+  reset(): void {
+    this.list.reset([]);
+    this.list.removeAllCallbacks();
+  }
 }

modules/angular2/src/core/compiler/query_list.dart

@@ -89,13 +89,6 @@ class QueryList<T> extends Object
     _dirty = true;
   }
 
-  // TODO(rado): hook up with change detection after #995.
-  void fireCallbacks() {
-    if (_dirty) {
-      _callbacks.forEach((c) => c());
-      _dirty = false;
-    }
-  }
 
   void onChange(callback) {
     _callbacks.add(callback);
@@ -105,6 +98,10 @@ class QueryList<T> extends Object
     _callbacks.remove(callback);
   }
 
+  void removeAllCallbacks() {
+    this._callbacks = [];
+  }
+
   int get length => _results.length;
   T get first => _results.first;
   T get last => _results.last;
@@ -116,4 +113,12 @@ class QueryList<T> extends Object
     // Note: we need to return a list instead of iterable to match JS.
     return this._results.map(fn).toList();
   }
+
+  // Internal to the framework.
+  void fireCallbacks() {
+    if (_dirty) {
+      _callbacks.forEach((c) => c());
+      _dirty = false;
+    }
+  }
 }

modules/angular2/src/core/compiler/query_list.ts

@@ -86,17 +86,13 @@ export class QueryList<T> {
     this._dirty = true;
   }
 
-  fireCallbacks(): void {
-    if (this._dirty) {
-      ListWrapper.forEach(this._callbacks, (c) => c());
-      this._dirty = false;
-    }
-  }
 
   onChange(callback: () => void): void { this._callbacks.push(callback); }
 
   removeCallback(callback: () => void): void { ListWrapper.remove(this._callbacks, callback); }
 
+  removeAllCallbacks(): void { this._callbacks = []; }
+
   toString(): string { return this._results.toString(); }
 
   get length(): number { return this._results.length; }
@@ -106,4 +102,12 @@ export class QueryList<T> {
   map<U>(fn: (item: T) => U): U[] { return this._results.map(fn); }
 
   [Symbol.iterator](): any { return this._results[Symbol.iterator](); }
+
+  // Internal to the framework.
+  fireCallbacks(): void {
+    if (this._dirty) {
+      ListWrapper.forEach(this._callbacks, (c) => c());
+      this._dirty = false;
+    }
+  }
 }

modules/angular2/test/core/compiler/query_integration_spec.ts

@@ -212,6 +212,34 @@ export function main() {
                  view.detectChanges();
                });
          }));
+
+      it('should correctly clean-up when destroyed together with the directives it is querying',
+         inject([TestComponentBuilder, AsyncTestCompleter], (tcb: TestComponentBuilder, async) => {
+           var template =
+               '<needs-query #q *ng-if="shouldShow"><div text="foo"></div></needs-query>';
+
+           tcb.overrideTemplate(MyComp, template)
+               .createAsync(MyComp)
+               .then((view) => {
+                 view.componentInstance.shouldShow = true;
+                 view.detectChanges();
+
+                 var q: NeedsQuery = view.componentViewChildren[1].getLocal('q');
+                 expect(q.query.length).toEqual(1);
+
+                 view.componentInstance.shouldShow = false;
+                 view.detectChanges();
+
+                 view.componentInstance.shouldShow = true;
+                 view.detectChanges();
+
+                 var q2: NeedsQuery = view.componentViewChildren[1].getLocal('q');
+
+                 expect(q2.query.length).toEqual(1);
+
+                 async.done();
+               });
+         }));
     });
 
     describe("querying by var binding", () => {

modules/angular2/test/core/compiler/query_list_spec.ts

@@ -92,6 +92,19 @@ export function main() {
         queryList.fireCallbacks();
         expect(fires).toEqual(1);
       });
+
+      it('should support removing all callbacks', () => {
+        var fires = 0;
+        var callback = () => fires += 1;
+        queryList.onChange(callback);
+
+        queryList.add('one');
+        queryList.removeAllCallbacks();
+
+        queryList.fireCallbacks();
+
+        expect(fires).toEqual(0);
+      });
     });
   });
 }