[Navigator]: Add a getter to get the current route that is focused from the navigation context.

Libraries/CustomComponents/Navigator/Navigation/__tests__/NavigationContext-test.js

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+/**
+ * Copyright (c) 2015, Facebook, Inc.  All rights reserved.
+ *
+ * Facebook, Inc. (“Facebook”) owns all right, title and interest, including
+ * all intellectual property and other proprietary rights, in and to the React
+ * Native CustomComponents software (the “Software”).  Subject to your
+ * compliance with these terms, you are hereby granted a non-exclusive,
+ * worldwide, royalty-free copyright license to (1) use and copy the Software;
+ * and (2) reproduce and distribute the Software as part of your own software
+ * (“Your Software”).  Facebook reserves all rights not expressly granted to
+ * you in this license agreement.
+ *
+ * THE SOFTWARE AND DOCUMENTATION, IF ANY, ARE PROVIDED "AS IS" AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES (INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE) ARE DISCLAIMED.
+ * IN NO EVENT SHALL FACEBOOK OR ITS AFFILIATES, OFFICERS, DIRECTORS OR
+ * EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THE SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+'use strict';
+
+jest
+  .dontMock('EmitterSubscription')
+  .dontMock('EventEmitter')
+  .dontMock('EventSubscriptionVendor')
+  .dontMock('NavigationContext')
+  .dontMock('NavigationEvent')
+  .dontMock('NavigationEventEmitter')
+  .dontMock('invariant');
+
+var NavigationContext = require('NavigationContext');
+
+describe('NavigationContext', () => {
+  it('defaults `currentRoute` to null', () => {
+    var context = new NavigationContext();
+    expect(context.currentRoute).toEqual(null);
+  });
+
+  it('updates `currentRoute`', () => {
+    var context = new NavigationContext();
+    context.emit('didfocus', {route: {name: 'a'}});
+    expect(context.currentRoute.name).toEqual('a');
+  });
+});
+
+