fix crash on feedlist collapse, do not use _COLLAPSED_FEEDLIST pref

include/functions.php

@@ -1966,7 +1966,6 @@
 		$params["max_feed_id"] = (int) $max_feed_id;
 		$params["num_feeds"] = (int) $num_feeds;
 
-		$params["collapsed_feedlist"] = (int) get_pref("_COLLAPSED_FEEDLIST");
 		$params["hotkeys"] = get_hotkeys_map();
 
 		$params["csrf_token"] = $_SESSION["csrf_token"];

js/tt-rss.js

@@ -789,19 +789,14 @@ function collapse_feedlist() {
 
 		if (!Element.visible('feeds-holder')) {
 			Element.show('feeds-holder');
-			Element.show('feeds-holder_splitter');
 			$("collapse_feeds_btn").innerHTML = "<<";
 		} else {
 			Element.hide('feeds-holder');
-			Element.hide('feeds-holder_splitter');
 			$("collapse_feeds_btn").innerHTML = ">>";
 		}
 
 		dijit.byId("main").resize();
 
-		query = "?op=rpc&method=setpref&key=_COLLAPSED_FEEDLIST&value=true";
-		new Ajax.Request("backend.php", { parameters: query });
-
 	} catch (e) {
 		exception_error("collapse_feedlist", e);
 	}