### Beta/Release Uplift Approval Request * **User impact if declined**: Broken layout, in pages where the optimization takes effect & where one of the known regressions happen to be triggered. * **Is this code covered by automated tests?**: Yes * **Has the fix been verified in Nightly?**: No * **Needs manual test from QE?**: No * **If yes, steps to reproduce**: * **List of other uplifts needed**: None * **Risk to taking this patch**: Low * **Why is the change risky/not risky? (and alternatives if risky)**: This change is just preffing off a recently-added opportunistic optimization (one which is probably activated infrequently, in the real world), because it's known to break layout in some cases. The optimization was only added in the Firefox 66 timeframe (bug 1159042), and we preffed it off in that release via bug 1527120, and this bug is just making that pref-off into a persistent thing. (I'm leaving it preffed on in Nightly and early-beta because the known regression isn't too bad.) * **String changes made/needed**: None
Bug 1547852 Comment 4 Edit History
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### Beta/Release Uplift Approval Request * **User impact if declined**: Broken layout, in pages where the optimization takes effect & where one of the known regressions happen to be triggered. * **Is this code covered by automated tests?**: Yes * **Has the fix been verified in Nightly?**: No * **Needs manual test from QE?**: No * **If yes, steps to reproduce**: * **List of other uplifts needed**: None * **Risk to taking this patch**: Low * **Why is the change risky/not risky? (and alternatives if risky)**: This change is just preffing off a recently-added opportunistic optimization (one which is probably activated infrequently, in the real world), because it's known to break layout in some cases. The optimization was only added in the Firefox 66 timeframe (bug 1159042), and we preffed it off in that release via bug 1527120, and this bug is just making that pref-off into a persistent thing. (I'm leaving it preffed on in Nightly and early-beta because the known regressions aren't too bad.) * **String changes made/needed**: None