Update test cases for DeviceOrientation Event

- Turn device_orientation_api.html and manifest.txt files into mainifest.txt and TODO.txt
- Remove t026.html as it has same checkpoints as screen-upmost.html, and merge values-null.html into screen-upmost.html
- Remove t030.html, t031.html, t032.html as they are incorrect in null attributes checking
- Rewrite other test cases