简洁语法模板内定义变量就出错了
原生语法定义变量，输出变量都没问题。

``` HTML
<!DOCTYPE HTML>
<html>
<head>
<meta charset="UTF-8">
<title>demo</title>
<script src="template.js"></script>
</head>
<body>
<script id="test" type="text/html">
{{var o = 'x'}}
{{o}}
</script>
<script>
var html = '';
html = template('test', {});
document.write(html);
</script>
</body>
</html>
```
