IE does not report render event after loaded event

[asheemmamoowala]

Moving forward from #8633 (comment)
@mannnick24 reported:

I believe there is now a race condition related to triggerRepaint in the map.render

in map.js is this
if (this._sourcesDirty || this._repaint || this._styleDirty || this._placementDirty) {
this.triggerRepaint();
} else if (!this.isMoving() && this.loaded()) {
this.fire(new Event('idle'));
}
and I think the tiles may not have loaded, but sourcesDirty could be false,

anyhoo, on IE we may or may not get a render after the map reports loaded() our product always waits for a a render with the map loaded (if dataloading) so our viz hangs in IE

Here is a fiddle, that may or may not trigger the fitbounds in IE - chrome seems to always pass
loadedrender.zip

Reproduction: https://jsbin.com/vovogurufe/edit?html,output

cc @kkaefer @kbauhausness

[juho-hanhimaki]

This was causing issues for us on IE so had to go back to v1.2.1.