版本：0.5.0-alpha2
- https://cdn.bootcdn.net/ajax/libs/html2canvas/0.5.0-alpha2/html2canvas.js
- https://cdn.bootcdn.net/ajax/libs/html2canvas/0.5.0-alpha2/html2canvas.min.js
- https://cdn.bootcdn.net/ajax/libs/html2canvas/0.5.0-alpha2/html2canvas.svg.js
- https://cdn.bootcdn.net/ajax/libs/html2canvas/0.5.0-alpha2/html2canvas.svg.min.js