Lay groudwork to Closure compile JavaScript

ui/webui/resources/js/parse_html_subset.js

Index: ui/webui/resources/js/parse_html_subset.js
diff --git a/ui/webui/resources/js/parse_html_subset.js b/ui/webui/resources/js/parse_html_subset.js
index c49d8fca89b47286c7e1927f741d5719ceb915b9..598af74f568796f986507dd4b93b82e56c1dc2e3 100644
--- a/ui/webui/resources/js/parse_html_subset.js
+++ b/ui/webui/resources/js/parse_html_subset.js
@@ -37,7 +37,8 @@ var parseHtmlSubset = (function() {
    */
   var allowedTags = ['A', 'B', 'STRONG'];
 
-  function merge() {
+  /** @param {...Object} var_args Objects to merge. */
+  function merge(var_args) {
     var clone = {};
     for (var i = 0; i < arguments.length; ++i) {
       if (typeof arguments[i] == 'object') {
@@ -75,7 +76,12 @@ var parseHtmlSubset = (function() {
     var tags = allowedTags.concat(extraTags);
     var attrs = merge(allowedAttributes, opt_extraAttrs || {});
 
-    var doc = document.implementation.createHTMLDocument('');
+    /** @suppress {missingProperties} */
+    function createDoc() {
+      return document.implementation.createHTMLDocument('');
+    }
+
+    var doc = createDoc();
     var r = doc.createRange();
     r.selectNode(doc.body);
     // This does not execute any scripts because the document has no view.