Improve code comments to save our efforts on re-evaluating the Browser supports. It helps to analysis Browser Hacks usages in CORE & Cleaning up in future releases.
This is how jQuery does also:
searching `// Support:`
the following patch I think OR condition is unnecessary but we don't have 100% confidence to remove it:
@import hack in CORE is also outdated I think:
- (Inform our CORE developer with right channel)
- (Discuss: Not rush for current source and only used in new hacks?)