Issue 7303 - Deprecate the use of String.prototype.substr()

lib/content/elemHideEmulation.js

Index: lib/content/elemHideEmulation.js
===================================================================
--- a/lib/content/elemHideEmulation.js
+++ b/lib/content/elemHideEmulation.js
@@ -423,21 +423,21 @@
   {
     for (let style of styles)
       if (regexp.test(style.style))
         for (let subSelector of style.subSelectors)
         {
           if (subSelector.startsWith("*") &&
               !incompletePrefixRegexp.test(prefix))
           {
-            subSelector = subSelector.substr(1);
+            subSelector = subSelector.substring(1);
           }
           let idx = subSelector.lastIndexOf("::");
           if (idx != -1)
-            subSelector = subSelector.substr(0, idx);
+            subSelector = subSelector.substring(0, idx);
           yield qualifySelector(subSelector, prefix);
         }
   }
 
   *getSelectors(prefix, subtree, styles, targets)
   {
     for (let selector of this.findPropsSelectors(styles, prefix, this._regexp))
       yield [selector, subtree];
@@ -639,17 +639,17 @@
       return [];
 
     let match = abpSelectorRegexp.exec(selector);
     if (!match)
       return [new PlainSelector(selector)];
 
     let selectors = [];
     if (match.index > 0)
-      selectors.push(new PlainSelector(selector.substr(0, match.index)));
+      selectors.push(new PlainSelector(selector.substring(0, match.index)));
 
     let startIndex = match.index + match[0].length;
     let content = parseSelectorContent(selector, startIndex);
     if (!content)
     {
       console.error(new SyntaxError("Failed to parse Adblock Plus " +
                                     `selector ${selector} ` +
                                     "due to unmatched parentheses."));
@@ -670,17 +670,17 @@
     {
       // this is an error, can't parse selector.
       console.error(new SyntaxError("Failed to parse Adblock Plus " +
                                     `selector ${selector}, invalid ` +
                                     `pseudo-class :-abp-${match[1]}().`));
       return null;
     }
 
-    let suffix = this.parseSelector(selector.substr(content.end + 1));
+    let suffix = this.parseSelector(selector.substring(content.end + 1));
     if (suffix == null)
       return null;
 
     selectors.push(...suffix);
 
     if (selectors.length == 1 && selectors[0] instanceof ContainsSelector)
     {
       console.error(new SyntaxError("Failed to parse Adblock Plus " +