Related to https://searchfox.org/wubkat/source/Source/WebCore/page/Quirks.cpp Currently the Quirks can be enabled/disabled through the Web Inspector. (Disable Site Specific Hacks feature) It's all or nothing. It means for a Website that would have multiple Quirks, it makes it harder to test individually if a specific Quirk can be removed because of the possible interactions. Currently, Disable Site Specific Hacks disables UA override as well.
<rdar://problem/117508103>