fix($StateRefDirective): resolve missing support for xlink:href angul…

…ar-ui#1667

Set the correct attribute when dealing with an SVG anchor element.
Otherwise, angular will prevent the click.

src/stateDirectives.js

@@ -86,9 +86,12 @@ function $StateRefDirective($state, $timeout) {
     link: function(scope, element, attrs, uiSrefActive) {
       var ref = parseStateRef(attrs.uiSref, $state.current.name);
       var params = null, url = null, base = stateContext(element) || $state.$current;
+      // SVGAElement does not use the href attribute, but rather the 'xlinkHref' attribute.
+      var hrefKind = toString.call(element.prop('href')) === '[object SVGAnimatedString]' ?
+                 'xlink:href' : 'href';	  
       var newHref = null, isAnchor = element.prop("tagName").toUpperCase() === "A";
       var isForm = element[0].nodeName === "FORM";
-      var attr = isForm ? "action" : "href", nav = true;
+      var attr = isForm ? "action" : hrefKind, nav = true;
 
       var options = { relative: base, inherit: true };
       var optionsOverride = scope.$eval(attrs.uiSrefOpts) || {};