Workaround required for atrocious performance of textarea fields in Chrome

[bobbingwide]

While developing oik-requests I started using textarea fields to store post meta data for information about files loaded, hooks invoked and queries performed. These fields can run to many many lines.
I noticed that in the WordPress edit page, pasting large amounts of data into the textarea fields brought Chrome to a standstill.

Google searches came up with the actual problem https://bugs.chromium.org/p/chromium/issues/detail?id=109587
but they didn't explain the easy workaround, which is to disable spell checking.
See http://stackoverflow.com/questions/254712/disable-spell-checking-on-html-textfields

So now we need a way to add the "spellcheck=false" parameter to selected textarea fields.
The lowest level API that might need changing is iarea(), though we could get away with changing the logic for displaying a sctextarea field using new logic.

As an aside

There are other things that might be good to have for input fields:

<input type="text" placeholder="My Field" name="myfield"
    autocapitalize="off" autocorrect="off" autocomplete="off" />

[bobbingwide]

The solution involves a change to oik-fields which will set fields of type 'sctextarea' to spellcheck="false" by default.

Note: The sc prefix is for "shortcode" not "spellcheck" nor "Slow/speedy Chrome".