Updates handling links on watermarks.

When link is missing disable clicking.

modules/UI/util/UIUtil.js

      */
     parseCssInt(cssValue) {
         return parseInt(cssValue) || 0;
+    },
+
+    /**
+     * Adds href value to 'a' link jquery object. If link value is null,
+     * undefined or empty string, disables the link.
+     * @param {object} aLinkElement the jquery object
+     * @param {string} link the link value
+     */
+    setLinkHref(aLinkElement, link) {
+        if (link) {
+            aLinkElement.attr('href', link);
+        } else {
+            aLinkElement.css({
+                "pointer-events": "none",
+                "cursor": "default"
+            });
+        }
     }
 };
 

modules/UI/videolayout/LargeVideo.js

 
             leftWatermarkDiv.css({display: 'block'});
 
-            leftWatermarkDiv.parent().attr(
-                'href', interfaceConfig.JITSI_WATERMARK_LINK);
+            UIUtil.setLinkHref(
+                leftWatermarkDiv.parent(),
+                interfaceConfig.JITSI_WATERMARK_LINK);
         }
 
         if (interfaceConfig.SHOW_BRAND_WATERMARK) {
                 backgroundImage: 'url(images/rightwatermark.png)'
             });
 
-            rightWatermarkDiv.parent().attr(
-                'href', interfaceConfig.BRAND_WATERMARK_LINK);
+            UIUtil.setLinkHref(
+                rightWatermarkDiv.parent(),
+                interfaceConfig.BRAND_WATERMARK_LINK);
         }
 
         if (interfaceConfig.SHOW_POWERED_BY) {

modules/UI/welcome_page/WelcomePage.js

 var animateTimeout, updateTimeout;
 
 var RoomnameGenerator = require("../../util/RoomnameGenerator");
+import UIUtil from "../util/UIUtil";
 
 function enter_room() {
     var val = $("#enter_room_field").val();
             $("#welcome_page_header div[class='watermark leftwatermark']");
         if(leftWatermarkDiv && leftWatermarkDiv.length > 0) {
             leftWatermarkDiv.css({display: 'block'});
-            leftWatermarkDiv.parent().get(0).href =
-                interfaceConfig.JITSI_WATERMARK_LINK;
+            UIUtil.setLinkHref(
+                leftWatermarkDiv.parent(),
+                interfaceConfig.JITSI_WATERMARK_LINK);
         }
-
     }
 
     if (interfaceConfig.SHOW_BRAND_WATERMARK) {
             $("#welcome_page_header div[class='watermark rightwatermark']");
         if(rightWatermarkDiv && rightWatermarkDiv.length > 0) {
             rightWatermarkDiv.css({display: 'block'});
-            rightWatermarkDiv.parent().get(0).href =
-                interfaceConfig.BRAND_WATERMARK_LINK;
+            UIUtil.setLinkHref(
+                rightWatermarkDiv.parent(),
+                interfaceConfig.BRAND_WATERMARK_LINK);
             rightWatermarkDiv.get(0).style.backgroundImage =
                 "url(images/rightwatermark.png)";
         }