add on dropdowns too small on 150% with wayland

[graingert]

After changing from laptop screen to 4k monitor, the dropdowns for addons are too small and do not fit the content, and text is blury. It appears as though firefox doesn't fully register the dpi change.

https://i.imgur.com/znlAQ66.png
https://i.imgur.com/y5Z5MPv.png

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: firefox 65.0+build2-0ubuntu0.18.10.1
ProcVersionSignature: Ubuntu 4.18.0-15.16-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.20.10-0ubuntu13.2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: graingert 2382 F.... pulseaudio
BuildID: 20190128173924
Channel: Unavailable
CurrentDesktop: ubuntu:GNOME
Date: Wed Feb 20 13:48:21 2019
Extensions: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
InstallationDate: Installed on 2019-02-15 (4 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
IpRoute:
 default via 10.9.0.1 dev wlp59s0 proto dhcp metric 600
 10.9.0.0/16 dev wlp59s0 proto kernel scope link src 10.9.98.239 metric 600
 10.11.0.0/16 via 10.9.0.129 dev wlp59s0 proto dhcp metric 600
 169.254.0.0/16 dev wlp59s0 scope link metric 1000
Locales: extensions.sqlite corrupt or missing
PrefSources: prefs.js
Profiles: Profile0 (Default) - LastVersion=65.0/20190128173924
RunningIncompatibleAddons: False
SourcePackage: firefox
Themes: extensions.sqlite corrupt or missing
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/15/2019
dmi.bios.vendor: LENOVO
dmi.bios.version: N20ET40W (1.25 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20KFCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN20ET40W(1.25):bd01/15/2019:svnLENOVO:pn20KFCTO1WW:pvrThinkPadX280:rvnLENOVO:rn20KFCTO1WW:rvrNotDefined:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad X280
dmi.product.name: 20KFCTO1WW
dmi.product.sku: LENOVO_MT_20KF_BU_Think_FM_ThinkPad X280
dmi.product.version: ThinkPad X280
dmi.sys.vendor: LENOVO