[Tracking Requested - why for this release]: About Nightly dialog is empty on Localized Build

Reproducible: always

Steps To Reproduce:

1. install [ja] build
   http://archive.mozilla.org/pub/firefox/nightly/2019/10/2019-10-19-09-53-21-mozilla-central-l10n/firefox-71.0a1.ja.win64.zip
2. Start the browser
3. Alt > ヘルプ(H) > Nightlyについて(A) ( Alt > Help > About Nightly )

Actual Results:
About Nightly dialog is empty

Expected Results:
About Nightly dialog shows properly

Regression window:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=a15ba287ac6fd84643d248ace00bf18c18382ada&tochange=27bbc1fba01518ef3f0ef836fb4a0473d8f71915

Error in Browser Console:

[Exception... "Component returned failure code: 0x80520012 (NS_ERROR_FILE_NOT_FOUND)
[nsIXPCComponents_Utils.readUTF8URI]" nsresult: "0x80520012 (NS_ERROR_FILE_NOT_FOUND)" location: "JS frame :: resource://gre/modules/L10nRegistry.jsm :: this.L10nRegistry.loadSync :: line 759" data: no] 6 L10nRegistry.jsm:759:19

[fluent] Missing translations in ja: menu-tools-fxa-sign-in, menu-tools-turn-on-sync, menu-tools-fxa-re-auth. Localization.jsm:202:13

Unknown category for SetEventRecordingEnabled: fxmonitor

No messages returned from https://snippets.cdn.mozilla.net/6/Firefox/71.0a1/2019101909…NT_x86_64-msvc/ja/nightly/Windows_NT%2010.0/default/default/. ASRouter.jsm:137

hbox 要素の XUL ボックスがインラインの子要素 #text を含んでいるため、すべての子はブロック中で折り返されます。 4 aboutDialog.xul

Works fine on macOS, but Japanese has different localization for Windows and macOS :-\

A couple of additional notes:

• Missing Fluent messages and the snippets error shouldn't be relevant for the problem. The first error is more interesting.
• I can't replicate this on the Italian build on Windows 10, so it seems to be either an issue in the Japanese localization, or in the pair of your OS+Nightly.

Does en-US work as expected on your system?

Also can't reproduce on Win10 ITA + Japanese Nightly (zip version)

I can also reproduce the issue on [it] build....
http://archive.mozilla.org/pub/firefox/nightly/2019/10/2019-10-19-09-53-21-mozilla-central-l10n/firefox-71.0a1.lt.win64.zip

Ugaaaa, I can also reproduce the issue on en-US build.

force enabled WebRender fixes the issue.

MozRegression:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=7f379c7775ca17056153d034647146b383bb6912&tochange=f6ca531ca5b2f282573ba0e1a9ca0e9f06046ac1

Regressed by: f6ca531ca5b2f282573ba0e1a9ca0e9f06046ac1 Alexis Beingessner — Bug 1573710 - make window resizing more robust to races. r=sotaro

Alexis Beingessner [:Gankra],

Your patch seems to cause the regression. Can you please look into this?

maybe this is same root cause, So, mark as duplicate of Bug 1589875

oof, bad time to catch a nasty cold, but looks like sotaro's on top of this now