Merge pull request #675 from hexid/fix-windows-tests

Fix error where this.emit('error', error); doesn't exist

@@ -387,7 +387,7 @@ Casper.prototype.checkStep = function checkStep(self, onComplete) {
         }
     } catch (error) {
         self.emit('complete.error', error);
-        this.emit('error', error);
+        self.emit('error', error);
     }
 };