perf(jqLite): only take str.split() path when needed

bda673f changed code to only use `str.split()` when necessary,
but the result was that `str.split()` would always be taken unless ' ' was the first character
in the string, negating the effectiveness of the perf fix.

Closes #8648

Author: caitp

src/jqLite.js

@@ -728,7 +728,7 @@ forEach({
     }
 
     // http://jsperf.com/string-indexof-vs-split
-    var types = type.indexOf(' ') ? type.split(' ') : [type];
+    var types = type.indexOf(' ') >= 0 ? type.split(' ') : [type];
     var i = types.length;
 
     while (i--) {