Started stubbing in the FlutterView property of the mock (flutter#20542)

FlutterViewControllers.

Author: gaaclarke

shell/platform/darwin/ios/framework/Source/accessibility_bridge_test.mm

@@ -339,6 +339,8 @@ - (void)testAnnouncesLayoutChangeWithNilIfLastFocusIsRemoved {
       /*rendering_api=*/flutter::IOSRenderingAPI::kSoftware,
       /*task_runners=*/runners);
   id mockFlutterViewController = OCMClassMock([FlutterViewController class]);
+  id mockFlutterView = OCMClassMock([FlutterView class]);
+  OCMStub([mockFlutterViewController view]).andReturn(mockFlutterView);
 
   NSMutableArray<NSDictionary<NSString*, id>*>* accessibility_notifications =
       [[[NSMutableArray alloc] init] autorelease];
@@ -402,6 +404,8 @@ - (void)testAnnouncesLayoutChangeWithLastFocused {
       /*rendering_api=*/flutter::IOSRenderingAPI::kSoftware,
       /*task_runners=*/runners);
   id mockFlutterViewController = OCMClassMock([FlutterViewController class]);
+  id mockFlutterView = OCMClassMock([FlutterView class]);
+  OCMStub([mockFlutterViewController view]).andReturn(mockFlutterView);
 
   NSMutableArray<NSDictionary<NSString*, id>*>* accessibility_notifications =
       [[[NSMutableArray alloc] init] autorelease];
@@ -472,6 +476,8 @@ - (void)testAnnouncesScrollChangeWithLastFocused {
       /*rendering_api=*/flutter::IOSRenderingAPI::kSoftware,
       /*task_runners=*/runners);
   id mockFlutterViewController = OCMClassMock([FlutterViewController class]);
+  id mockFlutterView = OCMClassMock([FlutterView class]);
+  OCMStub([mockFlutterViewController view]).andReturn(mockFlutterView);
 
   NSMutableArray<NSDictionary<NSString*, id>*>* accessibility_notifications =
       [[[NSMutableArray alloc] init] autorelease];