Fix classes used for detecting threads (#735)

* Fix classes used for detecting threads

* fix type issue

* simplify

Author: cancan101

src/gmail.js

@@ -283,9 +283,11 @@ var Gmail = function(localJQuery) {
         // There are currently two selectors in use for view_thread: Bu and nH,
         // Which correspond to two different ways a thread may be viewed by the user.
         // There are two different code paths to determine if we are within a thread.
+
         // This is the nH path:
-        // this should match the sub_selector (nH -> if)
-        var check_1 = $(".nH .if").children(":eq(1)").children().children(":eq(1)").children();
+        // this should match the sub_selector (nH -> if/iY):
+        var check_1 = $(".nH .if,.iY").children(":eq(1)").children().children(":eq(1)").children();
+
         // And this is the Bu path. We don't bother here checking for the sub_selector.
         var check_2 = api.get.email_ids();
 
@@ -2470,7 +2472,7 @@ var Gmail = function(localJQuery) {
             // which is triggered by the XHR request rather than nodes being inserted into the DOM (and thus returns different information)
             "view_thread": {
                 class: ["Bu", "nH"], // class depends if is_preview_pane - Bu for preview pane, nH for standard view
-                sub_selector: "div.if,div.PeIF1d",
+                sub_selector: "div.if,div.iY",
                 handler: function(match, callback) {
                     match = new api.dom.thread(match);
                     callback(match);
@@ -4473,7 +4475,7 @@ var Gmail = function(localJQuery) {
         }
 
         // this should match the sub_selector
-        if (!element || (!element.hasClass("if") && !element.hasClass("PeIF1d"))) api.tools.error("api.dom.thread called with invalid element/id");
+        if (!element || (!element.hasClass("if") && !element.hasClass("iY"))) api.tools.error("api.dom.thread called with invalid element/id");
         this.$el = element;
         return this;
     };