Change layout-rect to DOM-rect

[tiendt]

closes #6131

[jridgewell]

closes #6361

I don't think that's the right issue number.

[lannka]

My original thinking was to use the native data type DOMRect, so we can get rid of the custom LayoutRectDef or DOMRectDef, and together with both data converters DomRectFromLayoutRect and layoutRectFromDomRect.

However, @zhouyx pointed out DOMRect is not supported in Chrome :-(, so my proposal wasn't feasible.

I saw this PR changed LayoutRectDef to DOMRectDef, which still adds a bit value so that we can get rid of the DomRectFromLayoutRect converter. But since we still introduced a custom data type, shall we keep the original name LayoutRectDef?

[zhouyx]

Honestly I don't like that.. but I can't find a better solution. Or there's no better solution when different browsers are following different standard.... 😭
I would change our LayoutRect to use ClientRect and only convert them to DOMRect when we output them. But it's basically the same as converting everything to DOMRect first....

Whatever we do here, we need to name the function and doc them well....

[tiendt]

@lannka I'm sorry I misunderstood your proposal :( Should we discuss this further to make a proper change?

[lannka]

closing this, in favor of #10028