[cssom-view] Wanted: getBoundingClientRect() with logical property values

[dpogue]

Currently getBoundingClientRect() returns a DOMRect with top, right, bottom, and left properties corresponding to the position and size of the element.

This is great, but if you are trying to use it for calculating layout positions in an RTL context, you have to do things like rect.right - window.innerWidth to get the offset from the inline starting point.

Given that many CSS properties now support logical variants, it would be nice to have a function that returned the bounding box of an element using logical property names like blockStart, blockEnd, inlineStart, and inlineEnd.