RTE: Normalize Indent and Outdent operations in Editor

[Jared Jurkiewicz]

The indent and outdent code of the browser do not work very well. They're inconsistent about using blockquote versus div with padding ... and all browsers (IE, FF, WebKit?), indent/outdent lists wrong, they generate malformed lists.

So, like the EnterKeyHandling? plugin, it would be nice to have a way to handle indent/outdent consistently across browsers following a style indent pattern (much like other RTE do).

I have a prototype implementation that does this (and seems to work really well). It even fixes malformed lists from previous indent/outdent ops on a doc. It does not convert blockquote indent/outdent, though (not sure how to do that safely yet. Maybe as a prefilter operation to convert all blockquote tags to an indentable div).

[Jared Jurkiewicz]

Prototype of indent/outdent handler.

[Jared Jurkiewicz]

The prototype does the following:

1.) Uses customUndo on all browsers, as it has to manipulate the DOM directly.
2.) Fixes malformed lists (if they were created/indented wrong in the first place).

3.) Handles cross-selection indenting (indents elements that are indentable, will wrap inline elements within an indentable div as necessary.

Tests indicate that it seems to work really well. Feedback would be appreciated.

[Jared Jurkiewicz]

(In [20772]) Adding in experimental NormalizeIndentOutdent? for 1.4. Since experimental, is okay to add at this stage. \!strict fixes #10310

[Jared Jurkiewicz]

(In [20785]) Improving indent/outdent a bit to better handle multi-line select. refs #10310

[Jared Jurkiewicz]

(In [20786]) Dumb comment typo. refs #10310