this fixes under-reporting of active cosmetic filters in logger

src/js/contentscript-end.js

@@ -370,7 +370,7 @@ var uBlockCollapser = (function() {
                 processHighHighGenericsAsync();
             }
         }
-        if ( hideSelectors.length ) {
+        if ( hideSelectors.length !== 0 ) {
             addStyleTag(hideSelectors);
         }
         contextNodes.length = 0;
@@ -687,6 +687,12 @@ var uBlockCollapser = (function() {
             idsFromNodeList(selectNodes('[id]'));
             classesFromNodeList(selectNodes('[class]'));
             retrieveGenericSelectors();
+
+            // This is required: a new element could be matching an already
+            // injected but otherwise inactive cosmetic filter. This means
+            // the already injected cosmetic filter become active (has an
+            // effect on the document), and thus must be logged if needed.
+            messager.send({ what: 'cosmeticFiltersActivated' });
         }
     };
 

src/js/contentscript-start.js

@@ -140,7 +140,7 @@ var filteringHandler = function(details) {
     // This is just to inform the background process that cosmetic filters were
     // actually injected.
     if ( vAPI.styles.length !== styleTagCount ) {
-        localMessager.send({ what: 'cosmeticFiltersInjected' });
+        localMessager.send({ what: 'cosmeticFiltersActivated' });
     }
 
     // https://github.com/chrisaljoudi/uBlock/issues/587

src/js/cosmetic-logger.js

@@ -68,10 +68,10 @@ while ( i-- ) {
     if ( loggedSelectors.hasOwnProperty(selector) ) {
         continue;
     }
-    loggedSelectors[selector] = true;
     if ( document.querySelector(selector) === null ) {
         continue;
     }
+    loggedSelectors[selector] = true;
     matchedSelectors.push(selector);
 }
 

src/js/messaging.js

@@ -62,10 +62,9 @@ var onMessage = function(request, sender, callback) {
         break;
 
     case 'cosmeticFiltersInjected':
-        // Is this a request to cache selectors?
-        if ( Array.isArray(request.selectors) ) {
         µb.cosmeticFilteringEngine.addToSelectorCache(request);
-        }
+        /* falls through */
+    case 'cosmeticFiltersActivated':
         // Net-based cosmetic filters are of no interest for logging purpose.
         if ( µb.logger.isObserved(tabId) && request.type !== 'net' ) {
             µb.logCosmeticFilters(tabId);