This removes some hackery surrounding preventing content clicks, and in
general handles auxclick as it should, firing that event on secondary
buttons (wheel/right on default setup for right-handed mouse).
Based on selected bits of M-C 1461708:
- EventStateManager::CheckForAndDispatchClick() to early-return style
- split EventStateManager::CheckForAndDispatchClick() into:
EventCausesClickEvents, PostHandleMouseUp, DispatchClickEvents
- Move implementation of UIEvent::GetRangeParent() and UIEvent::RangeOffset() to nsLayoutUtils
ScrollbarStyles contains values of overflow, (over)scroll-behavior, etc.
The only one which is marginally related to scroll _bars_ is overflow, which can
be used to hide scrollbar (by making an element not scrollable) or enforce the
scrollbar to display.
It makes more sense to be called ScrollStyles as it's mainly concerning behavior
of scrolling, not scrollbars. Also, with the addition of scrollbar width
properties, the current name can be confusing.
Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
