Rather than abusing variable-3. Coloring is the same for now.

(when there is a gutter)

Issue #4637

This is based on work by Radek Piórkowski <radek25c@gmail.com>.

This reverts commit a44e76a0.

Issue #4606

So that line widgets aren't included in the background style

Closes #4606

Ligatures were disabled since some editors didn’t allow placing the cursor inside of them.

“Contextual alternatives” on the other hand still allow this, therefore this commit enables them to support e.g. Fira Code’s main gimmick.

Closes #4253

Indentation should happen top-to-bottom so that subsequent
indents are based on the updated code above

Issue #4248

Closes #4248

Closes #4233

Issue #4091

Issue #4091

See https://discuss.codemirror.net/t/addoverlay-removeoverlay-and-opaque/835

Closes #4113

Fixes issue #4163.

In some cases, on wrapping points, they span the whole line

Issue #4097

Chrome would show the IME widget too high because it noticed the textarea
was cut off by the wrapping DIV.

Issue #4095

Closes #4090

Closes #4087