fix(datepicker): rxjs throws error on component destroy

* The datepicker expects the `backdropClick()` observable to emit one value before the observable completes. If no click happened and the component gets destroyed RxJS throws an error because no value got emitted.
* Monkey-patches Angular's TestBed to properly report errors on component destroy.

Author: devversion

src/lib/datepicker/datepicker.ts

@@ -257,7 +257,7 @@ export class MdDatepicker<D> implements OnDestroy {
       this._ngZone.onStable.first().subscribe(() => this._popupRef.updatePosition());
     }
 
-    this._popupRef.backdropClick().first().subscribe(() => this.close());
+    this._popupRef.backdropClick().subscribe(() => this.close());
   }
 
   /** Create the popup. */

test/karma-test-shim.js

@@ -87,9 +87,38 @@ function configureTestBed() {
 
     jasmine.DEFAULT_TIMEOUT_INTERVAL = 10000;
 
-    testing.TestBed.initTestEnvironment(
+    var testBed = testing.TestBed.initTestEnvironment(
       testingBrowser.BrowserDynamicTestingModule,
       testingBrowser.platformBrowserDynamicTesting()
     );
+
+    applyAngularTestingPatches(testBed);
+  });
+}
+
+/** Applies patches and workarounds to Angular's testing package. */
+function applyAngularTestingPatches(testBed) {
+  // Original resetTestingModule function of the TestBed.
+  var _resetTestingModule = testBed.resetTestingModule;
+
+  // Monkey-patch the resetTestingModule to destroy fixtures outside of a try/catch block.
+  // With https://github.com/angular/angular/commit/2c5a67134198a090a24f6671dcdb7b102fea6eba
+  // errors when destroying components are no longer causing Jasmine to fail.
+  testBed.resetTestingModule = function() {
+    try {
+      this._activeFixtures.forEach(function (fixture) { fixture.destroy(); });
+    } finally {
+      this._activeFixtures = [];
+      // Regardless of errors or not, run the original reset testing module function.
+      _resetTestingModule.call(this);
+    }
+  };
+
+  // Angular's testing package resets the testing module before each test. This is bad because
+  // it doesn't allow developers to see what test actually failed. Fixing this by resetting
+  // the testing module after each test.
+  // https://github.com/angular/angular/blob/master/packages/core/testing/src/before_each.ts#L25
+  afterEach(function() {
+    testBed.resetTestingModule();
   });
 }