- Add tests for the button element
- fix the typo issues
- Resolve issues
1. The assertion of cancelable attribute.
2. The assertion of assertion descriptions.
3. The event handle pattern and etc.
- Update the last assertion of the show event test
- Resolve issues
1. Remove the trailing ws
2. Move evt.preventDefault() into the test
3. Add a test to check the button type, and put the click() method into it.
4. Remove the reset-form.html, etc
- Fix a typo issue in the assertion description
- Use t.step to check the button type
- Update the event registeration method as review sugguestion

Signed-off-by: xiaojunwu <xiaojunx.a.wu@intel.com>