Bug 36430

Currently, InsertListCommand has three major problems: 1. If the selection contains more than one paragraphs, modifyRange() loops over each paragraph and calls doApply. This is very misleading because doApply() and modifyRange() aren't really mutually recursive functions (doApply() calls modifyRange() at most once when doApply() is called for the first time). 2. doApply() has two parts; the first part removes the child node and the second part adds list. Although there are cases in which we remove a list element and add a different type of list element later, two parts are sufficiently isolated and they should be separate functions. 3. IndentOutdentCommand and InsertListCommand implements very similar features but do not share much code. IndentOutdentCommand adds and removes list just like InsertListCommand, and the only difference is that InsertListCommand sometimes needs to wrap a paragraph with LI whereas IndentOutdentCommand wraps with a blockquote in such cases. Two classes should share more code. Proposal: we first divide doApply into two separate functions/methods. We then move the code inside of modifyRange into doApply. We can then combine code in IndentOutdentCommand and InsertListCommand.