use default threshold for share elements

Readability.js

@@ -579,9 +579,12 @@ Readability.prototype = {
 
     // Clean out elements with little content that have "share" in their id/class combinations from final top candidates,
     // which means we don't remove the top candidates even they have "share".
+
+    var shareElementThreshold = this.DEFAULT_CHAR_THRESHOLD
+    
     this._forEachNode(articleContent.children, function (topCandidate) {
       this._cleanMatchedNodes(topCandidate, function (node, matchString) {
-        return /share/.test(matchString) && node.textContent.length < 500;
+        return /share/.test(matchString) && node.textContent.length < shareElementThreshold;
       });
     });