Issue 6538, 6781 - Minimize access to ElemHideBase's selector property

lib/elemHide.js

Index: lib/elemHide.js
===================================================================
--- a/lib/elemHide.js
+++ b/lib/elemHide.js
@@ -120,19 +120,20 @@
    * Add a new element hiding filter
    * @param {ElemHideBase} filter
    */
   add(filter)
   {
     if (knownFilters.has(filter))
       return;
 
+    let {selector} = filter;
+
     if (filter instanceof ElemHideException)
     {
-      let {selector} = filter;
       let list = exceptions.get(selector);
       if (list)
         list.push(filter);
       else
         exceptions.set(selector, [filter]);
 
       // If this is the first exception for a previously unconditionally
       // applied element hiding selector we need to take care to update the
@@ -140,20 +141,20 @@
       let unconditionalFilterForSelector = filterBySelector.get(selector);
       if (unconditionalFilterForSelector)
       {
         addToFiltersByDomain(unconditionalFilterForSelector);
         filterBySelector.delete(selector);
         unconditionalSelectors = null;
       }
     }
-    else if (!(filter.domains || exceptions.has(filter.selector)))
+    else if (!(filter.domains || exceptions.has(selector)))
     {
       // The new filter's selector is unconditionally applied to all domains
-      filterBySelector.set(filter.selector, filter);
+      filterBySelector.set(selector, filter);
       unconditionalSelectors = null;
     }
     else
     {
       // The new filter's selector only applies to some domains
       addToFiltersByDomain(filter);
     }
 
@@ -165,28 +166,30 @@
    * Removes an element hiding filter
    * @param {ElemHideBase} filter
    */
   remove(filter)
   {
     if (!knownFilters.has(filter))
       return;
 
+    let {selector} = filter;
+
     // Whitelisting filters
     if (filter instanceof ElemHideException)
     {
-      let list = exceptions.get(filter.selector);
+      let list = exceptions.get(selector);
       let index = list.indexOf(filter);
       if (index >= 0)
         list.splice(index, 1);
     }
     // Unconditially applied element hiding filters
-    else if (filterBySelector.get(filter.selector) == filter)
+    else if (filterBySelector.get(selector) == filter)
     {
-      filterBySelector.delete(filter.selector);
+      filterBySelector.delete(selector);
       unconditionalSelectors = null;
     }
     // Conditionally applied element hiding filters
     else
     {
       let domains = filter.domains || defaultDomains;
       for (let domain of domains.keys())
       {
@@ -196,25 +199,25 @@
       }
     }
 
     knownFilters.delete(filter);
     FilterNotifier.emit("elemhideupdate");
   },
 
   /**
-   * Checks whether an exception rule is registered for a filter on a particular
-   * domain.
-   * @param {Filter} filter
+   * Checks whether an exception rule is registered for a selector on a
+   * particular domain.
+   * @param {string} selector
    * @param {?string} docDomain
    * @return {?ElemHideException}
    */
-  getException(filter, docDomain)
+  getException(selector, docDomain)
   {
-    let list = exceptions.get(filter.selector);
+    let list = exceptions.get(selector);
     if (!list)
       return null;
 
     for (let i = list.length - 1; i >= 0; i--)
     {
       if (list[i].isActiveOnDomain(docDomain))
         return list[i];
     }
@@ -247,20 +250,24 @@
       if (filters)
       {
         for (let [filter, isIncluded] of filters)
         {
           if (!isIncluded)
           {
             excluded.add(filter);
           }
-          else if ((excluded.size == 0 || !excluded.has(filter)) &&
-                   !this.getException(filter, domain))
+          else
           {
-            selectors.push(filter.selector);
+            let {selector} = filter;
+            if ((excluded.size == 0 || !excluded.has(filter)) &&
+                !this.getException(selector, domain))
+            {
+              selectors.push(selector);
+            }
           }
         }
       }
 
       if (currentDomain == "")
         break;
 
       let nextDot = currentDomain.indexOf(".");