1117156 - When starting mochitests: "chrome://browser/content/tabbrowser.xml, line 5293: ReferenceError: reference to undefined property getComputedStyle(...).width"

Status: NEW

(Firefox :: General, defect)

Description

[Daniel Holbert [:dholbert]]

I noticed this go by in my terminal-spew when starting up mochitests:
{
JavaScript strict warning: chrome://browser/content/tabbrowser.xml, line 5293: ReferenceError: reference to undefined property getComputedStyle(...).width
}

The exact command I used was "./mach mochitest-plain dom/svg/test/test_pathLength.html". I tried twice and saw this warning both times.

(I didn't see the warning go by when I started a full mochitest-run with "./mach mochitest-plain", so I think this might only happen when you specify a specific mochitest on the command line.  But I might've just missed it.)

The warning points to the last quoted line here:
{
> 5303   <binding id="statuspanel" display="xul:hbox">
[...]
> 5315     <implementation implements="nsIDOMEventListener">
[...]
> 5325       <property name="label">
> 5326         <setter><![CDATA[
[...]
> 5332           this.style.minWidth = this.getAttribute("type") == "status" &&
> 5333                                 this.getAttribute("previoustype") == "status"
> 5334                                   ? getComputedStyle(this).width : "";
}
https://mxr.mozilla.org/mozilla-central/source/browser/base/content/tabbrowser.xml#5334
(MXR's line numbering is slightly off from the line number given in the warning, since chrome://browser/content/tabbrowser.xml seems to be preprocessed)

Dao, looks like you added this line in bug 629898 and then tweaked it in bug 631298. Do you know what's going on here?

Comment 1

[Dão Gottwald [:dao]]

Sorry, I don't know why getComputedStyle would behave this way.