[ADF-4647] download service (#4836)

* split download api into separate service

* move tests and fix code

* break dependency for thumbnail service

* update tests

* test fixes

* fix code

* fix unit tests

lib/core/services/download.service.spec.ts

@@ -0,0 +1,39 @@
+/*!
+ * @license
+ * Copyright 2019 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { DownloadService } from './download.service';
+
+describe('DownloadService', () => {
+    let service: DownloadService;
+
+    beforeEach(() => {
+        service = new DownloadService();
+    });
+
+    describe('Download blob', () => {
+        it('Should use native msSaveOrOpenBlob if the browser is IE', (done) => {
+            const navigatorAny: any = window.navigator;
+
+            navigatorAny.__defineGetter__('msSaveOrOpenBlob', () => {
+                done();
+            });
+
+            const blob = new Blob([''], { type: 'text/html' });
+            service.downloadBlob(blob, 'test_ie');
+        });
+    });
+});