Show alt text when source image is missing or broken or not found.

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index 4ff133a93087e36213903e5f7c3ea0e5bef786cd..bcd8938fa2fa9af86e684df71b4be562def40a3e 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -885,6 +885,26 @@ crbug.com/361729 fast/multicol/pagination-h-horizontal-tb.html [ Pass Failure ]
 crbug.com/359877 virtual/regionbasedmulticol/fast/multicol/mixed-opacity-fixed-test.html [ ImageOnlyFailure ]
 crbug.com/359877 virtual/regionbasedmulticol/fast/multicol/mixed-opacity-test.html [ ImageOnlyFailure ]
 
+#alt Text layout tests rebaseline
+crbug.com/157207 crbug.com/773 editing/selection/select-missing-image.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/block/float/002.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/block/float/015.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/block/positioning/061.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/encoding/utf-16-big-endian.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/encoding/utf-16-little-endian.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/forms/002.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/forms/005.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/lists/inlineBoxWrapperNullCheck.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/text/bidi-img-alt-text.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/text/whitespace/normal-after-nowrap-breaking.html   [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 tables/mozilla/bugs/bug2997.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 tables/mozilla/bugs/bug4527.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 tables/mozilla/collapsing_borders/bug41262-3.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 [ Mac Win ] virtual/antialiasedtext/fast/text/bidi-img-alt-text.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 [ Mac Win ] virtual/antialiasedtext/fast/text/whitespace/normal-after-nowrap-breaking.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/dom/HTMLImageElement/image-alt-text-no-width.html [ NeedsRebaseline ]
+crbug.com/157207 crbug.com/773 fast/dom/HTMLImageElement/image-alt-text-width.html [ NeedsRebaseline ]
+
 # Old multicol tests that currently have no baseline in the virtual test suite
 # for the new multicol implementation.
 crbug.com/386567 virtual/regionbasedmulticol/fast/multicol/border-padding-pagination.html [ Skip ]