Revert "refactor: use isObservable provided by rxjs 6.1+ (#27668)"

This reverts commit 7e6350ce2e.

packages/core/src/core_private_export.ts

@@ -30,7 +30,7 @@ export {global as ɵglobal} from './util/global';
 export {looseIdentical as ɵlooseIdentical,} from './util/comparison';
 export {stringify as ɵstringify} from './util/stringify';
 export {makeDecorator as ɵmakeDecorator} from './util/decorators';
-export {isPromise as ɵisPromise} from './util/lang';
+export {isObservable as ɵisObservable, isPromise as ɵisPromise} from './util/lang';
 export {clearOverrides as ɵclearOverrides, initServicesIfNeeded as ɵinitServicesIfNeeded, overrideComponentView as ɵoverrideComponentView, overrideProvider as ɵoverrideProvider} from './view/index';
 export {NOT_FOUND_CHECK_ONLY_ELEMENT_INJECTOR as ɵNOT_FOUND_CHECK_ONLY_ELEMENT_INJECTOR} from './view/provider';
 export {LocaleDataIndex as ɵLocaleDataIndex, CurrencyIndex as ɵCurrencyIndex, ExtraLocaleDataIndex as ɵExtraLocaleDataIndex, getLocalePluralCase as ɵgetLocalePluralCase, findLocaleData as ɵfindLocaleData, registerLocaleData as ɵregisterLocaleData, unregisterAllLocaleData as ɵunregisterLocaleData} from './i18n/locale_data_api';

packages/core/src/render3/instructions/listener.ts

@@ -6,8 +6,9 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {isObservable} from 'rxjs';
+
 import {assertDataInRange} from '../../util/assert';
+import {isObservable} from '../../util/lang';
 import {EMPTY_OBJ} from '../empty';
 import {PropertyAliasValue, TNode, TNodeFlags, TNodeType} from '../interfaces/node';
 import {GlobalTargetResolver, RElement, Renderer3, isProceduralRenderer} from '../interfaces/renderer';

packages/core/src/util/BUILD.bazel

@@ -15,5 +15,6 @@ ts_library(
     deps = [
         "//packages:types",
         "//packages/core/src/interface",
+        "@npm//rxjs",
     ],
 )

packages/core/src/util/lang.ts

@@ -6,6 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {Observable} from 'rxjs';
+
 /**
  * Determine if the argument is shaped like a Promise
  */
@@ -14,3 +16,12 @@ export function isPromise(obj: any): obj is Promise<any> {
   // It's up to the caller to ensure that obj.then conforms to the spec
   return !!obj && typeof obj.then === 'function';
 }
+
+/**
+ * Determine if the argument is an Observable
+ */
+export function isObservable(obj: any | Observable<any>): obj is Observable<any> {
+  // TODO: use isObservable once we update pass rxjs 6.1
+  // https://github.com/ReactiveX/rxjs/blob/master/CHANGELOG.md#610-2018-05-03
+  return !!obj && typeof obj.subscribe === 'function';
+}

packages/core/src/view/provider.ts

@@ -6,13 +6,13 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {isObservable} from 'rxjs';
 import {ChangeDetectorRef, SimpleChange, SimpleChanges, WrappedValue} from '../change_detection/change_detection';
 import {INJECTOR, Injector, resolveForwardRef} from '../di';
 import {ElementRef} from '../linker/element_ref';
 import {TemplateRef} from '../linker/template_ref';
 import {ViewContainerRef} from '../linker/view_container_ref';
 import {Renderer2} from '../render/api';
+import {isObservable} from '../util/lang';
 import {stringify} from '../util/stringify';
 
 import {createChangeDetectorRef, createInjector} from './refs';