Fix closure compile.

http://build.chromium.org/p/chromium.fyi/builders/Closure%20Compilation%20Linux/builds/14594/steps/compile/logs/stdio

TBR=kalman@chromium.org
BUG=none
TEST=green closure bots

Review URL: https://codereview.chromium.org/907553003

Cr-Commit-Position: refs/heads/master@{#315154}

chrome/browser/resources/extensions/extensions.js

@@ -380,7 +380,7 @@ cr.define('extensions', function() {
   ExtensionSettings.showOverlay = function(node) {
     var pageDiv = $('extension-settings');
     pageDiv.style.width = node ? window.getComputedStyle(pageDiv).width : '';
-    document.body.classList.toggle('no-scroll', node);
+    document.body.classList.toggle('no-scroll', !!node);
 
     var currentlyShowingOverlay = ExtensionSettings.getCurrentOverlay();
     if (currentlyShowingOverlay) {

ui/webui/resources/js/cr/ui/page_manager/page.js

@@ -23,7 +23,7 @@ cr.define('cr.ui.pageManager', function() {
     this.name = name;
     this.title = title;
     this.pageDivName = pageDivName;
-    this.pageDiv = $(this.pageDivName);
+    this.pageDiv = getRequiredElement(this.pageDivName);
     // |pageDiv.page| is set to the page object (this) when the page is visible
     // to track which page is being shown when multiple pages can share the same
     // underlying div.