rdar://127246368 https://bugs.webkit.org/show_bug.cgi?id=275221 Reviewed by Sammy Gill. We won't try to adjust computed font sizes if (visibleWidth >= width()) at RenderBlockFlow::adjustComputedFontSizes. On the first load, RenderBlockFlow::width is calculated to a value that allows TextAutoSizing to set new computed font sizes for the text nodes on the page. Width is much larger than visibleWidth, ultimately coming from WebPageProxy::textAutosizingWidth which returns WebCore::screenSize().width(). At refresh,RenderBlockFlow::width returns a value that is actually equal to visibleWidth (and screenSize().width()). There seems to depend on timing. I wasn't able to reproduce that when simulator CPU load was too high. Since the page where the bug manifests itself already has responsive CSS styling, we can quirk TextAutoSizing to skip adjusting for it, at least until we figure out why we are calculating RenderBlockFlow width inconsistently: https://bugs.webkit.org/show_bug.cgi?id=275223 * Source/WebCore/page/LocalFrameViewLayoutContext.cpp: (WebCore::LocalFrameViewLayoutContext::applyTextSizingIfNeeded): * Source/WebCore/page/Quirks.cpp: (WebCore::Quirks::skipTextAutoSizing const): * Source/WebCore/page/Quirks.h: Canonical link: https://commits.webkit.org/279788@main