Reproduced the initial issue with an old Nightly build 78.0a1 (2020-05-15) using Windows 10. Verified - Fixed in latest Beta 78.0b5 (build id: 20200609165924) and latest Nightly 79.0a1 (build id: 20200610043607). The pref is true by default in both channels mentioned above.
Bug 1636855 Comment 51 Edit History
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Reproduced the initial issue with an old Nightly build 78.0a1 (2020-05-15) using Windows 10. Verified - Fixed in latest Beta 78.0b5 (build id: 20200609165924) and latest Nightly 79.0a1 (build id: 20200610043607) using Windows 10 and Ubuntu 18.04. The pref is true by default in both channels mentioned above.