fix($StateRefDirective): resolve travis warnings.

Fix mixed spaces and tabs.

Author: martinoss

src/stateDirectives.js

@@ -88,7 +88,7 @@ function $StateRefDirective($state, $timeout) {
       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';	  
+                 'xlink:href' : 'href';
       var newHref = null, isAnchor = element.prop("tagName").toUpperCase() === "A";
       var isForm = element[0].nodeName === "FORM";
       var attr = isForm ? "action" : hrefKind, nav = true;