[ContentEditable] Infinite script loop can be easily fired

[Frederico Caldeira Knabben]

1. Load the following HTML:

<p>Para 1</p>
<p><span contenteditable="false">Non Editable</span></p>
<p>Para 2</p>

2. Hit CTRL+A to select all.

3. Click the indentation button.

Current results:

The script will loop, blocking the browser. This happens when creating lists also.

Expected results:

All paragraphs (including the one with the read only content) should get indented.

This one is related to the ​contenteditable feature branch.

[Frederico Caldeira Knabben]

This happens even for inline operations, like applying styles.

[Garry Yao]

Infinite loop fixed with [5595], leave open for the unexpected result: Only first two paragraphs get indented.

[Garry Yao]

Second issue is committed as [5599].

[Frederico Caldeira Knabben]

WFM now. Code review will be done all in a row on the branch.