Use var keyword when declaring local variable so it doesn't leak to global scope.

Author: trevordixon

src/lib/style-properties.html

@@ -270,7 +270,7 @@
       applyElementScopeSelector: function(element, selector, old, viaAttr) {
         var c = viaAttr ? element.getAttribute(styleTransformer.SCOPE_NAME) :
           element.className;
-        v = old ? c.replace(old, selector) :
+        var v = old ? c.replace(old, selector) :
           (c ? c + ' ' : '') + this.XSCOPE_NAME + ' ' + selector;
         if (c !== v) {
           if (viaAttr) {