make location accessors not NPE when doc.loc not set

qunit wants to look at the location to see if the doc is local or remote (though it doesn't currently use this). But envjs errors out if you ask for fields; make it return nothing

src/window/location.js

@@ -90,7 +90,7 @@ $w.__defineGetter__("location", function(url){
 				this.search + this.hash;
 		},
 		get protocol(){
-			return protocol.exec(this.href)[0];
+			return this.href && protocol.exec(this.href)[0];
 		},
 		set protocol(_protocol){
 			$w.location = _protocol + this.host + this.pathname +