929757 - Animating transform incorrectly affects height of containing element

Status: RESOLVED DUPLICATE of bug 928607

(Core :: Layout, defect)

Description

[Mike Pennisi [:jugglinmike]]

Attachment: 907177-overflow-scroll.html

Given three nested elements A, B, and C, where C is taller than B:

    +-----------+
    |A          |
    | +-------+ |
    | |B      | |
    | | +---+ | |
    | | | C | | |
    | | |   | | |
    | +-------+ |
    |   |   |   |
    |   +---+   |
    +-----------+

If B declares `overflow-y: hidden;` and C's `transform` attribute is modified, then A expands to contain C (even though B continues to "mask" C correctly).

I've attached a reduced test case that demonstrates this behavior in Firefox Nightly 27.0a1 (2013-10-22).

This was first discovered in Gaia--see bug 907177. As mentioned there, we believe this regression was introduced with the following commit: http://hg.mozilla.org/mozilla-central/rev/45d9e6cd3473

Comment 1

[James Lal [:lightsofapollo]]

@roc could you comment?