Error on adding attribute with specified value

Version: 0.9.4 and 0.9.5

Tried the code from an [example](https://hyperscript.org/commands/add/):

``` html
Disable Other Buttons
```

but got an error:

```
[Error] hyperscript errors were found on the following element: (4)
Disable Other Buttons"

""Unexpected Token : =

on click add @disabled='true' to when it is not me
^^

"c — core.js:1149parseHyperScript — core.js:1169R — core.js:1896(анонимная функция) — core.js:1876a — core.js:1430processNode — core.js:1872e — core.js:5638
R (_hyperscript_web.min.js:1:16892)
(анонимная функция) (_hyperscript_web.min.js:1:17879)
a (_hyperscript_web.min.js:1:14554)
processNode (_hyperscript_web.min.js:1:17813)
e (_hyperscript_web.min.js:1:69299)
```

使用 HTML 示例重现该问题，并检查 core.js:1149 和 core.js:1169 中报告的解析器位置。检查 add 命令如何解析 @disabled='true'，然后验证该示例不再产生 Unexpected Token 错误。

由索引模型根据 Issue 内容生成。