navigation MDL-14632 Very significant navigation commit

This patch introduces two new blocks global_navigation_tree and settings_navigation_tree
both of which have been designed to make full use of the new navigation objects available through
the $PAGE object.
Bulk of this code is within lib/navigationlib.php

lib/javascript-static.js

@@ -721,18 +721,45 @@ function addonload(fn) {
             fn();
     }
 }
-
-function getElementsByClassName(oElm, strTagName, oClassNames) {
+/**
+ * Replacement for getElementsByClassName in browsers that aren't cool enough
+ * 
+ * Relying on the built-in getElementsByClassName is far, far faster than
+ * using YUI.
+ * 
+ * Note: the third argument used to be an object with odd behaviour. It now
+ * acts like the 'name' in the HTML5 spec, though the old behaviour is still
+ * mimicked if you pass an object.
+ *
+ * @param {Node} oElm The top-level node for searching. To search a whole
+ *                    document, use `document`.
+ * @param {String} strTagName filter by tag names
+ * @param {String} name same as HTML5 spec
+ */
+function getElementsByClassName(oElm, strTagName, name) {
+    // for backwards compatibility
+    if(typeof name == "object") {
+        var names = new Array();
+        for(var i=0; i<name.length; i++) names.push(names[i]);
+        name = names.join('');
+    }
+    // use native implementation if possible
+    if (oElm.getElementsByClassName && Array.filter) {
+        if (strTagName == '*') {
+            return oElm.getElementsByClassName(name);
+        } else {
+            return Array.filter(oElm.getElementsByClassName(name), function(el) {
+                return el.nodeName.toLowerCase() == strTagName.toLowerCase();
+            });
+        }
+    }
+    // native implementation unavailable, fall back to slow method
     var arrElements = (strTagName == "*" && oElm.all)? oElm.all : oElm.getElementsByTagName(strTagName);
     var arrReturnElements = new Array();
     var arrRegExpClassNames = new Array();
-    if(typeof oClassNames == "object") {
-        for(var i=0; i<oClassNames.length; i++) {
-            arrRegExpClassNames.push(new RegExp("(^|\\s)" + oClassNames[i].replace(/\-/g, "\\-") + "(\\s|$)"));
-        }
-    }
-    else{
-        arrRegExpClassNames.push(new RegExp("(^|\\s)" + oClassNames.replace(/\-/g, "\\-") + "(\\s|$)"));
+    var names = name.split(' ');
+    for(var i=0; i<names.length; i++) {
+        arrRegExpClassNames.push(new RegExp("(^|\\s)" + names[i].replace(/\-/g, "\\-") + "(\\s|$)"));
     }
     var oElement;
     var bMatchesAll;