586653 - Regression - MozBackgroundSize present in document.documentElement.style

Status: RESOLVED INVALID

(Core :: CSS Parsing and Computation, defect)

Description

[Mike Kaply [:mkaply]]

In Firefox 4, -moz-background-size was changed to background-size.

The proper way to check for this is:

if ("MozBackgroundSize" in document.documentElement.style) {

In Firefox 4 Beta 2 , this worked.

In Firefox 4 beta 3, this is returning true.

Comment 1

[Boris Zbarsky [:bzbarsky]]

This worksforme with a trunk build.  Are you sure you were testing beta3?

Comment 2

[Mike Kaply [:mkaply]]

Yep, I was testing beta 3. I'll check again.

Comment 3

[Mike Kaply [:mkaply]]

Strange. There was a change in behavior, but it's not what I thought.

I'm doing the wrong thing in my code at some point:

(root is #main-window)

	  if (aData.backgroundSize) {
		root.style.MozBackgroundSize = aData.backgroundSize;
	  } else {
		root.style.MozBackgroundSize = "";
	  }

without regards to FF4 or previous (need to fix that).

But in the previous Firefox 3 beta, this didn't affect document.documentElement.style but in beta 3 it does.

Any ideas?

I'll fix my code, but there is still something weird going on here...

Comment 4

[Boris Zbarsky [:bzbarsky]]

> Any ideas?

Well, the previous behavior certainly sounded buggy....

Note that expandos on .style might be gc-sensitive; I don't recall.

Comment 5

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Yes, expandos on style are GC-sensitive.

Comment 6

[Mike Kaply [:mkaply]]

This is invalid then.