insertHtml and insertElement should agree on the result

[Garry Yao]

Currently CKEDITOR.editor.insertHtml and CKEDITOR.editor.insertElement are having different results when the inserted element happened to be malformed or schema-violated.
This is because insertHtml is depending some native methods like pasteHtml to perform revision, from which the result may vary from browser to browser. While insertElement is all about our own logic, which perform no revision at all( The revision logic is proposing at #3100 though).

[Garry Yao]

The attached test case's result are different from FF to IE to Webkit.

[Garry Yao]

Functional Test Case

[Frederico Caldeira Knabben]

Milestone CKEditor 3.x deleted

[Piotrek Koszuliński]

Over the years meaning of these methods changed. Currently both are implemented using only our custom code, but insertHtml is more "external" (it does clean up and filtering) when insertElement is an "internal" method (I do not mean that it is private, but that it does not handle input, invalid data).