Issue 6727 - Avoid getter for multi-domain cases

lib/filterClasses.js

Index: lib/filterClasses.js
===================================================================
--- a/lib/filterClasses.js
+++ b/lib/filterClasses.js
@@ -395,39 +395,31 @@
 
   /**
    * Map containing domains that this filter should match on/not match
    * on or null if the filter should match on all domains
    * @type {?Map.<string,boolean>}
    */
   get domains()
   {
-    let prop = Object.getOwnPropertyDescriptor(this, "_domains");
-    if (prop)
-    {
-      let {value} = prop;
-      return typeof value == "string" ?
-               new Map([[value, true], ["", false]]) : value;
-    }
-
     let domains = null;
 
     if (this.domainSource)
     {
       let source = this.domainSource;
       if (!this.domainSourceIsLowerCase)
       {
         // RegExpFilter already have lowercase domains
         source = source.toLowerCase();
       }
       let list = source.split(this.domainSeparator);
       if (list.length == 1 && list[0][0] != "~")
       {
         // Fast track for the common one-domain scenario
-        domains = list[0];
+        Object.defineProperty(this, "_singleDomain", {value: list[0]});
       }
       else
       {
         let hasIncludes = false;
         for (let i = 0; i < list.length; i++)
         {
           let domain = list[i];
           if (domain == "")
@@ -441,29 +433,35 @@
           }
           else
           {
             include = true;
             hasIncludes = true;
           }
 
           if (!domains)
+          {
             domains = new Map();
+            Object.defineProperty(this, "domains", {value: domains});
+          }
 
           domains.set(domain, include);
         }
         if (domains)
           domains.set("", !hasIncludes);
       }
 
       this.domainSource = null;
     }
 
-    Object.defineProperty(this, "_domains", {value: domains});
-    return this.domains;
+    let singleDomain = this._singleDomain;
+    if (singleDomain)
+      return new Map([[singleDomain, true], ["", false]]);
+
+    return domains;
   },
 
   /**
    * Array containing public keys of websites that this filter should apply to
    * @type {?string[]}
    */
   sitekeys: null,