Before this commit, there was an issue with input method using
composition in which typed characters were duplicated.
This was occuring until the composition ended.
This is a bug specific to Google Chrome v53+.
It has been fixed in the most recent version of ace.js [1],
and we just port the fix into our custom code.
Note that we do not simply import ace.js as a whole, because
we must update lots of custom code at the same time.
We plan to do so in the future.
Fixes#23629
[1] https://github.com/ajaxorg/ace/pull/3116