Settings cleanup: Remove obsolete setTimeout() work-around.

This workaround refers to 859794 which is obsolete after removal of
page/subpage animations.

Bug: 859794
Change-Id: I688ec714117f90a797db1b1baacc6eb9d2138751
Reviewed-on: https://chromium-review.googlesource.com/c/1490436Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Reviewed-by: calamity <calamity@chromium.org>
Commit-Queue: calamity <calamity@chromium.org>
Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636347}

chrome/browser/resources/settings/global_scroll_target_behavior.js

@@ -41,8 +41,7 @@ cr.define('settings', function() {
 
       /**
        * The |subpageScrollTarget| should only be set for this route.
-       * @type {settings.Route}
-       * @private
+       * @private {settings.Route}
        */
       subpageRoute: Object,
 
@@ -58,20 +57,7 @@ cr.define('settings', function() {
 
     /** @param {!settings.Route} route */
     currentRouteChanged: function(route) {
-      // Immediately set the scroll target to active when this page is
-      // activated, but wait a task to remove the scroll target when the page is
-      // deactivated. This gives scroll handlers like iron-list a chance to
-      // handle scroll events that are fired as a result of the route changing.
-      // TODO(https://crbug.com/859794): Having this timeout can result some
-      // jumpy behaviour in the scroll handlers. |this.active_| can be set
-      // immediately when this bug is fixed.
-      if (route == this.subpageRoute) {
-        this.active_ = true;
-      } else {
-        setTimeout(() => {
-          this.active_ = false;
-        });
-      }
+      this.active_ = route == this.subpageRoute;
     },
 
     /**