Use Shadow DOM to display fallback content for images

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index 320b6903f8b3306582b41e8ce8da17378ca996f3..0937b470b5805f43b57b9e1f24a532b16be251a5 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -3698,6 +3698,24 @@ crbug.com/350853 fast/multicol/widows2.html [ Skip ]
 crbug.com/350853 fast/pagination/auto-height.html [ Skip ]
 crbug.com/350853 fast/pagination/auto-height-with-break.html [ Skip ]
 
+
+crbug.com/419101 [ Mac ] compositing/color-matching/pdf-image-match.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] css1/box_properties/float_elements_in_series.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] editing/selection/select-missing-image.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] fast/forms/002.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] fast/forms/005.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] fast/images/image-in-map.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] fast/overflow/infiniteRecursion.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] fast/parser/comment-in-script.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] fast/table/008.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] http/tests/misc/image-blocked-src-change.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] inspector/extensions/extensions-network.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] tables/mozilla/bugs/bug56201.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] tables/mozilla_expected_failures/bugs/bug23847.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] virtual/deferred/fast/images/image-in-map.html [ NeedsRebaseline ]
+crbug.com/419101 [ Mac ] virtual/implsidepainting/inspector/tracing/paint-command-log-nodes.html [ NeedsRebaseline ]
+crbug.com/410949 http/tests/security/local-image-from-remote-whitelisted.html [ Failure ]
+
 crbug.com/374569 [ Win ] http/tests/navigation/beacon-cross-origin.html [ Pass Failure Timeout ]
 crbug.com/374572 svg/filters/feImage-target-reappend-to-document.svg [ Pass Failure ]
 crbug.com/374572 svg/dynamic-updates/SVGImageElement-svgdom-preserveAspectRatio-prop.html [ Pass ImageOnlyFailure ]