Remove useragent checking for various goog.events.BrowserFeature properties:
Remove useragent checking for various goog.events.BrowserFeature properties:

* HAS_W3C_BUTTON
* HAS_W3C_EVENT_SUPPORT
* HAS_NAVIGATOR_ONLINE_PROPERTY
* HAS_HTML5_NETWORK_EVENT_SUPPORT

These are now always true.  Also sets some workaround features to permanently false:

* SET_KEY_CODE_TO_PREVENT_DEFAULT
* HTML5_NETWORK_EVENTS_FIRE_ON_BODY

Assuming this sticks, we will delete all the special handling for older browsers in a future change.

RELNOTES[INC]: Removed some goog.events support for IE8- era browsers.

PiperOrigin-RevId: 353969984

google/closure-library,google/closure-library,google/closure-library,google/closure-library,google/closure-library