HTML Features only in 0 or 1 browsers...

In our telecon today (https://lists.w3.org/Archives/Public/public-html/2016Apr/0001.html), we talked about enumerating a set of HTML 5.1 features that might not meet a minimum bar for inclusion: are the implemented in at least 2 browsers?

To answer this question, we turned to the API Catalog (https://aka.ms/apicatalog) and filtered out the non-HTML 5.1 features. The raw data used is attached (CSV file). We did a little spreadsheet math to find columns where APIs were only supported in 0 or 1 browsers. Here's the high-level summary:

No browser supports:
============
Canvas Proxies
dragexit
table sorting
misc. <area> attributes (hreflang, type)
autocomplete (textarea/select)
ImageBitmap Factories
force spell check
Media Controller
misc. <input> props (valueHigh/valueLow)
Content handler registration
SVG root element global event handlers

1 browser supports:

Autocomplete Error event (Chrome)
DataCue (Edge)
Search Provider registration
<details> (Chrome)
<dialog> (Chrome)
<marquee> (Edge) (obsolete section)
<menuitem> (Chrome)
<style scoped> (Firefox)
<textarea inputmode> (Chrome)
minLength (textarea) (Chrome)
location.assign (Edge)
PromiseRejectionEvent (Chrome)
RelatedEvent object (Chrome)
ShowModalDialog (Safari)
document.load (Firefox)