Allow browser's native spell checker in editing area

[sphakka]

According to this post, adding these attributes

contenteditable="true" spellcheck="true"

to the editing area node <div id="editor" ...> allows the browser's native spell checker to work properly.

Until ACE reacts to this, the following patch does the trick:

--- editor.js.orig      2017-08-20 15:03:44.853698240 +0200
+++ editor.js   2017-08-20 15:06:18.843948351 +0200
@@ -280,7 +280,7 @@
                container.html(
                        '<div id="editor_overlay"></div>'
                        +'<div id="editor_container" class="icon-loading">'
-                       +'<div id="editor_wrap"><div id="editor"></div>'
+                       +'<div id="editor_wrap"><div id="editor" contenteditable="true" spellcheck="true"></div>'
                        +'<div id="preview_wrap"><div id="preview"></div></div></div></div>');
                $('#app-content').append(container);
 

Tested on FireFox-52.2 and SeaMonkey-2.48 :-) Mind that, wrt plain text areas, spell checking options in the browser's context menu have no effect...