Add some missing rendering code to textual feed stories

Summary: Ref T2852. Token given stories currently try to `strip_tags()` a `PHUIFeedView` or similar, which doesn't work. Cast it to a string before stripping. This is super gross but I don't want to clean it up until after ApplicationTransactions so we can really clean up all of Feed.

Test Plan: Ran `bin/feed republish <id>` on a feed story about giving a token to a revision.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2852

Differential Revision: https://secure.phabricator.com/D6733

src/applications/tokens/feed/PhabricatorTokenGivenFeedStory.php

@@ -35,7 +35,7 @@ final class PhabricatorTokenGivenFeedStory
 
   public function renderText() {
     // TODO: This is grotesque; the feed notification handler relies on it.
-    return strip_tags($this->renderView()->render());
+    return strip_tags(hsprintf('%s', $this->renderView()->render()));
   }
 
 }

src/applications/transactions/feed/PhabricatorApplicationTransactionFeedStory.php

@@ -57,7 +57,7 @@ class PhabricatorApplicationTransactionFeedStory
 
   public function renderText() {
     // TODO: This is grotesque; the feed notification handler relies on it.
-    return strip_tags($this->renderView()->render());
+    return strip_tags(hsprintf('%s', $this->renderView()->render()));
   }
 
 }