Disable Share extension item receiver if there is no app group.

EGTests don't have the application group entitlement.
Disable the Receiver in that case.

BUG=675412

Review-Url: https://codereview.chromium.org/2588683002
Cr-Commit-Position: refs/heads/master@{#439754}

ios/chrome/browser/share_extension/share_extension_item_receiver.mm

@@ -98,13 +98,9 @@ void LogHistogramReceivedItem(ShareExtensionItemReceived type) {
   DCHECK(!_readingListModel);
   DCHECK(!_bookmarkModel);
 
-#if TARGET_IPHONE_SIMULATOR
   if (![self presentedItemURL]) {
     return;
   }
-#else
-  DCHECK([self presentedItemURL]);
-#endif
 
   _readingListModel = readingListModel;
   _bookmarkModel = bookmarkModel;