fix: specify dimensions in iframe demo

[crookedneighbor]

If you go to https://krakenjs.com/zoid/demo/basic/iframe/index.htm, you'll see that the iframe login is missing.

This is because the dimensions aren't being passed, so the height and width are being set to undefined.

Passing the dimensions fixes the issue:

A broader question I have is whether or not dimensions should be a required attribute or not. Currently, it's not marked as required in the docs: https://github.com/krakenjs/zoid/blob/master/docs/api/create.md#dimensions--width--string-height--string-

[bluepnume]

Thanks! Yeah dimensions should not be required, they should be defaulted when not passed. Can you take a look why the defaults are not kicking in?

[crookedneighbor]

@bluepnume looks to me like default dimensions are being applied for popups, but not iframes:

zoid/src/parent/parent.js

Lines 621 to 622 in a4c1564

	} else if (context === CONTEXT.POPUP && __ZOID__.__POPUP_SUPPORT__) {
	let { width = DEFAULT_DIMENSIONS.WIDTH, height = DEFAULT_DIMENSIONS.HEIGHT } = getDimensions();