ContentDonUnload should be fired by all editables when they are detached.
Changelog entries.
Merge branch 't/11131b'
Makes code more readable and ready to future changes.
Check id offset == container.length before enlarge end.
Check whitespaces using walker instead of regexp.
Removed unneeded condition from walker.guard.
Compile regexp.
Added comment to onlyWhiteSpaces.
Re-used the regex.