1668969 - remove scrolling="no" from mochitest harness iframe

Status: NEW

(Testing :: Mochitest, task)

Description

[Timothy Nikkel (:tnikkel)]

I discovered in bug 1656689, comment 16 that the iframe that the mochitest harness uses to run tests in has scrolling="no" set on it, here

https://searchfox.org/mozilla-central/rev/7ef5cefd0468b8f509efe38e0212de2398f4c8b3/testing/mochitest/server.js#824

This is different from almost every other document that we ever see, so we shouldn't be doing this for tests.

One place this effects is ScrollFrameHelper::GetScrollStylesFromFrame

https://searchfox.org/mozilla-central/rev/7ef5cefd0468b8f509efe38e0212de2398f4c8b3/layout/generic/nsGfxScrollFrame.cpp#4429

I noticed the same thing about the mochitest-chrome harness in bug 1199023, but this uses an unusual way to add scrolling=no that would be hard to search for.

I tried to look up the history for this, it seems to be back to 2007 when the mochitest harness was added.

We fail a handful of tests when this is removed that will have to be fixed in order to fix this

https://treeherder.mozilla.org/#/jobs?repo=try&revision=a50f3facfb0e1236a92c295dc9ef41d584229d6b

Comment 1

[Andrew Halberstadt [:ahal]]

Clearing stale needinfos (please re-request if still needed)

Comment 2

[Timothy Nikkel (:tnikkel)]

Please don't clear needindos that you didn't set and are not asking you for info.

Comment 3

[Andrew Halberstadt [:ahal]]

My apologies, fwiw these fill my triage centre Todo list.