Use a non-replaced inline container for image alt text

third_party/WebKit/LayoutTests/fast/dom/HTMLImageElement/fallback-image-moved-across-documents.html

Index: third_party/WebKit/LayoutTests/fast/dom/HTMLImageElement/fallback-image-moved-across-documents.html
diff --git a/third_party/WebKit/LayoutTests/fast/dom/HTMLImageElement/fallback-image-moved-across-documents.html b/third_party/WebKit/LayoutTests/fast/dom/HTMLImageElement/fallback-image-moved-across-documents.html
index 11017f40f744ec60f101653997b4afc40b7811f0..1ee4cc2b004fa287f9c91d9bc8b335c727832bbb 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/HTMLImageElement/fallback-image-moved-across-documents.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/HTMLImageElement/fallback-image-moved-across-documents.html
@@ -37,7 +37,7 @@ promise_test(t => {
   return eventWatcher.wait_for("error").then(_ => {
     window.setTimeout(_ => document.body.append(i));
     return eventWatcher.wait_for("error").then(_ => {
-      assert_equals(i.clientWidth, 20, "Fallback content should be displayed.");
+      assert_equals(i.clientWidth, 16, "Fallback content should be displayed.");
     });
   });
 }, "Infinitely nested fallback content shadow trees should not be created, or this test will never terminate.");