Should fix #1862 for ltr text.

This variable was unused after 0e545326.

when forced after compositionend event.

Issue #4441

Since the input object might try to read from that on focusing

Issue #4439

Closes #4412

Issue #4417

Issue #4307

when accessing `document.activeElement` from inside an iframe.

So that the code doesn't get confused when backspacing or
deleting across a line.

This is still flaky. Ideally we'd capture backspace as a key event,
but Android Chrome makes that impossible.

Issue #4307

Rather than on read

And do so only after a delay, so that subsequent input
events get a chance to fire.

Because Android, especially Google Keyboard, just doesn't care

So that the selection isn't reset to the start of the element by
div.focus().

And use it in the merge addon to get the proper offsets for merge buttons

Issue #4364

When selecting at the beginning of a line ranges need to be removed
for new range to be added properly. (in Safari)

Issue #4289

Because it has nothing to do with measurement.

And don't put indentation in css strings.

Issue #4312

With non-empty selections, transposeChar would only work on the chars next to
head and ignore the selected chars. Also, a cursor at line start was not moved
on successful swapping.