Issue 7046 - Defer caching of domain maps

lib/elemHide.js

Index: lib/elemHide.js
===================================================================
--- a/lib/elemHide.js
+++ b/lib/elemHide.js
@@ -106,21 +106,21 @@
   }
 
   return domain;
 }
 
 /**
  * Adds a filter to the lookup table of filters by domain.
  * @param {Filter} filter
+ * @param {?Map.<string,boolean>} [domains]
  */
-function addToFiltersByDomain(filter)
+function addToFiltersByDomain(filter, domains = filter.domains)
 {
-  let domains = filter.domains || defaultDomains;
-  for (let [domain, isIncluded] of domains)
+  for (let [domain, isIncluded] of domains || defaultDomains)
   {
     // There's no need to note that a filter is generically disabled.
     if (!isIncluded && domain == "")
       continue;
 
     let filters = filtersByDomain.get(domain);
     if (!filters)
       filtersByDomain.set(domain, filters = new Map());
@@ -280,29 +280,29 @@
    */
   add(filter)
   {
     if (knownFilters.has(filter))
       return;
 
     commonStyleSheet = null;
 
-    let {selector} = filter;
+    let {domains, selector} = filter;

[Manish Jethani, 2018/10/15 15:36:59]

Here we are just minimizing access to the domains getter.

 
-    if (!(filter.domains || ElemHideExceptions.hasExceptions(selector)))
+    if (!(domains || ElemHideExceptions.hasExceptions(selector)))
     {
       // The new filter's selector is unconditionally applied to all domains
       filterBySelector.set(selector, filter);
       unconditionalSelectors = null;
       defaultStyleSheet = null;
     }
     else
     {
       // The new filter's selector only applies to some domains
-      addToFiltersByDomain(filter);
+      addToFiltersByDomain(filter, domains);
     }
 
     knownFilters.add(filter);
     filterNotifier.emit("elemhideupdate");
   },
 
   /**
    * Removes an element hiding filter