Fixes#3559
For some reason, Chromium 37 is not compositing scrollbars correctly on
secondary monitors in OS X. They’re invisible when the lines layer
extends beneath the scrollbars unless we apply this style.
* Simplify scrollbar refresh and measurement by using imperative DOM
manipulation instead of React to hide/show scrollbars.
* Rename `::performInitialMeasurement` to `::becameVisible`
* Break `::checkForVisibilityChange` out of `::pollDOM` and use it in
to check for the element becoming visible in `componentWillUpdate`.
* Don't rely on stored visibility state anywhere. Always check again.
This could potentially be cached for an update cycle but being wrong
about this is disastrous so I'm being conservative.
This fork of React allows data-react-skip-selection-restoration to be
defined on input elements, skipping costly selection restoration that
occurs when the input element is focused during reconciliation.
Previously, dummy scrollbars were always 15px wide/tall. This caused
them to obscure the ability to click for the entire 15px region, even if
the actual scrollbar was styled to be much thinner. Now we explicitly
measure the size of scrollbars on mount and when the stylesheets change
and set the height/width explicitly.
This entailed quite a few changes to dial in scrollbars. The scrollbars
are now adjusted in size to account for the width of the opposite
scrollbar. If the width or height are not explicitly constrained and we
are scrollable in the opposite direction that is constrained, we account
for the width of the opposite scrollbar in assigning a natural height
or width based on the content.
We set overflow to hidden in the opposite scroll direction only if we
can't actually scroll in that direction, causing the white square where
neither scrollbar overlaps to appear at the lower right corner.
It checks that the incoming scrollTop/Left and scrollHeight/Width differ
from their current values. The scrollTop/Left value are updated in
the component properties to always reflect the state of the DOM when
scrolling or when assigning a new value.
