Bug 266533

As it is, when doing analysis of results from no-failure-limits runs on EWS, there's no way to distinguish what's a pre-existing failure from what's a novel failure (though obviously we can't find flakiness, given a single run without retries). This means if you try to rebaseline based on the results with `./Tools/Scripts/update-test-expectations github-pr` or similar you'll rebaseline far too much. And we don't want any sort of automation to accidentally rebaseline too much. (Though obviously ideally we wouldn't have pre-existing failures in the tree!) For example, after re-importing imported/w3c/web-platform-tests/dom (https://ews-build.webkit.org/#/builders/36/builds/27895 for mac-wk2) after running update-text-expectations: gsnedders@gsnedders-marsha OS2 % git add 'LayoutTests/imported/w3c/web-platform-tests/dom' LayoutTests/platform/*/imported/w3c/web-platform-tests/dom gsnedders@gsnedders-marsha OS2 % git status On branch wpt-dom-import Your branch is up to date with 'fork/wpt-dom-import'. Changes to be committed: (use "git restore --staged <file>..." to unstage) new file: LayoutTests/imported/w3c/web-platform-tests/dom/events/Event-dispatch-single-activation-behavior-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/events/remove-all-listeners-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/events/scrolling/scrollend-event-fires-to-iframe-window-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/events/scrolling/scrollend-with-snap-on-fractional-offset-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/observable/tentative/observable-constructor.any-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/observable/tentative/observable-constructor.any.worker-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/observable/tentative/observable-constructor.window-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/observable/tentative/observable-event-target.any-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/observable/tentative/observable-event-target.any.worker-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/basic-dom-part-declarative-brace-syntax-innerhtml.tentative-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/basic-dom-part-declarative-brace-syntax.tentative-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/basic-dom-part-declarative-pi-syntax.tentative-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/basic-dom-part-objects.tentative-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/dom-parts-parseparts-on-body.tentative-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/dom-parts-parseparts-on-head.tentative-expected.txt new file: LayoutTests/imported/w3c/web-platform-tests/dom/parts/dom-parts-parseparts-on-root.tentative-expected.txt new file: LayoutTests/platform/gtk/imported/w3c/web-platform-tests/dom/events/Event-dispatch-single-activation-behavior-expected.txt new file: LayoutTests/platform/wpe/imported/w3c/web-platform-tests/dom/events/Event-dispatch-single-activation-behavior-expected.txt Changes not staged for commit: (use "git add/rm <file>..." to update what will be committed) (use "git restore <file>..." to discard changes in working directory) modified: LayoutTests/compositing/layer-creation/scale-rotation-transition-overlap-expected.txt modified: LayoutTests/http/tests/webgpu/webgpu/api/operation/rendering/stencil-expected.txt modified: LayoutTests/http/tests/xmlhttprequest/resetting-timeout-to-zero-expected.txt modified: LayoutTests/imported/w3c/web-platform-tests/html/canvas/element/fill-and-stroke-styles/2d.fillStyle.get.transparent-expected.txt modified: LayoutTests/imported/w3c/web-platform-tests/mathml/relations/css-styling/padding-border-margin/margin-003-expected.txt modified: LayoutTests/imported/w3c/web-platform-tests/permissions/permissions-garbage-collect.https-expected.txt modified: LayoutTests/platform/gtk/editing/selection/triple-click-in-pre-expected.txt modified: LayoutTests/platform/gtk/fast/forms/time/time-input-rendering-basic-expected.txt modified: LayoutTests/platform/gtk/imported/w3c/web-platform-tests/accname/name/comp_host_language_label-expected.txt modified: LayoutTests/platform/gtk/svg/repaint/text-repainting-after-modifying-transform-repaint-rects-expected.txt modified: LayoutTests/platform/wpe/fast/table/text-field-baseline-expected.txt modified: LayoutTests/platform/wpe/fast/text/softbank-emoji-expected.txt modified: LayoutTests/platform/wpe/imported/w3c/web-platform-tests/css/css-cascade/all-prop-initial-xml-expected.txt deleted: LayoutTests/platform/wpe/imported/w3c/web-platform-tests/css/css-masking/inheritance.sub-expected.txt modified: LayoutTests/platform/wpe/imported/w3c/web-platform-tests/webxr/ar-module/xrDevice_requestSession_immersive-ar.https-expected.txt deleted: LayoutTests/platform/wpe/imported/w3c/web-platform-tests/workers/modules/shared-worker-import-referrer-expected.txt modified: LayoutTests/platform/wpe/svg/custom/invisible-text-after-scrolling-expected.txt modified: LayoutTests/platform/wpe/svg/repaint/text-repainting-after-modifying-transform-repaint-rects-expected.txt modified: LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-mainframe-vertical-then-horizontal-expected.txt Untracked files: (use "git add <file>..." to include in what will be committed) LayoutTests/platform/gtk/compositing/layer-creation/scale-rotation-transition-overlap-expected.txt LayoutTests/platform/gtk/fast/events/monotonic-event-time-expected.txt LayoutTests/platform/gtk/fast/preloader/ LayoutTests/platform/gtk/http/tests/resourceLoadStatistics/ LayoutTests/platform/gtk/imported/w3c/web-platform-tests/css/css-align/blocks/align-content-block-003-expected.txt LayoutTests/platform/gtk/imported/w3c/web-platform-tests/css/css-break/ LayoutTests/platform/gtk/imported/w3c/web-platform-tests/css/css-transitions/ LayoutTests/platform/gtk/imported/w3c/web-platform-tests/editing/run/ LayoutTests/platform/gtk/imported/w3c/web-platform-tests/html/cross-origin-opener-policy/ LayoutTests/platform/gtk/imported/w3c/web-platform-tests/media-source/ LayoutTests/platform/gtk/imported/w3c/web-platform-tests/webcodecs/ LayoutTests/platform/gtk/media/modern-media-controls/ LayoutTests/platform/gtk/perf/ LayoutTests/platform/gtk/svg/repaint/text-repainting-after-modifying-container-transform-repaint-rects-expected.txt LayoutTests/platform/gtk/webrtc/ LayoutTests/platform/ios-wk2/compositing/layer-creation/scale-rotation-transition-overlap-expected.txt LayoutTests/platform/ios-wk2/fast/forms/ios/ LayoutTests/platform/ios-wk2/fast/scrolling/ios/scroll-anchoring-momentum-scroll-expected.txt LayoutTests/platform/ios-wk2/http/tests/xmlhttprequest/ LayoutTests/platform/ios-wk2/platform/ LayoutTests/platform/ios-wk2/requestidlecallback/ LayoutTests/platform/mac-wk1/compositing/layer-creation/scale-rotation-transition-overlap-expected.txt LayoutTests/platform/mac-wk1/http/tests/cache/ LayoutTests/platform/mac-wk1/http/tests/loading/main-resource-delegates-on-back-navigation-expected.txt LayoutTests/platform/mac-wk1/http/tests/media/ LayoutTests/platform/mac-wk1/http/tests/websocket/tests/hybi/client-close-2-expected.txt LayoutTests/platform/mac-wk1/imported/w3c/web-platform-tests/html/semantics/interactive-elements/ LayoutTests/platform/wpe/css3/scroll-snap/ LayoutTests/platform/wpe/fast/canvas/webgl/tex-image-and-sub-image-2d-with-video-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/tex-image-and-sub-image-2d-with-video-rgb565-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/tex-image-and-sub-image-2d-with-video-rgba4444-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/tex-image-and-sub-image-2d-with-video-rgba5551-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/texImage2D-mse-flipY-false-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/texImage2D-mse-flipY-true-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/texImage2D-mse-in-dom-flipY-false-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/texImage2D-mse-in-dom-flipY-true-expected.txt LayoutTests/platform/wpe/fast/canvas/webgl/texImage2D-video-flipY-false-expected.txt LayoutTests/platform/wpe/fast/mediastream/MediaStream-video-element-displays-buffer-expected.txt LayoutTests/platform/wpe/fast/mediastream/mediastreamtrack-video-zoom-expected.txt LayoutTests/platform/wpe/fast/mediastream/resize-trim-expected.txt LayoutTests/platform/wpe/fast/preloader/ LayoutTests/platform/wpe/fullscreen/exit-full-screen-video-crash-expected.txt LayoutTests/platform/wpe/http/wpt/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/css/css-align/blocks/align-content-block-002-expected.txt LayoutTests/platform/wpe/imported/w3c/web-platform-tests/css/css-break/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/css/css-transitions/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/editing/run/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/html/cross-origin-opener-policy/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/html/dom/idlharness.https_include=HTML._-expected.txt LayoutTests/platform/wpe/imported/w3c/web-platform-tests/html/semantics/embedded-content/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/html/semantics/selectors/pseudo-classes/inrange-outofrange-expected.txt LayoutTests/platform/wpe/imported/w3c/web-platform-tests/media-source/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/preload/ LayoutTests/platform/wpe/imported/w3c/web-platform-tests/webcodecs/ LayoutTests/platform/wpe/media/media-source/ LayoutTests/platform/wpe/scrollbars/ LayoutTests/platform/wpe/svg/repaint/text-repainting-after-modifying-container-transform-repaint-rects-expected.txt LayoutTests/platform/wpe/webgl/ LayoutTests/platform/wpe/webrtc/