Add checks for READMEs for each virtual test suite.

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index 784cc8bdb878b8a6648516130a3ba6e59a2bec05..7dd9213c0262f74c76304107153cb60e3d477a59 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -1079,6 +1079,10 @@ crbug.com/380151 fast/events/only-valid-drop-targets-receive-file-drop.html [ Fa
 
 crbug.com/380649 [ Mac ] fast/dom/HTMLScriptElement/dont-load-unknown-type.html [ Failure ]
 
+# We only want to run one of the web-animations-api tests in stable mode.
+crbug.com/368946 virtual/stable/web-animations-api [ Skip ]
+crbug.com/368946 virtual/stable/web-animations-api/eased-keyframes.html [ Pass ]
+
 # Temporarily skipped until Chromium side change lands.
 crbug.com/308768 http/tests/security/XFrameOptions/x-frame-options-deny-meta-tag-in-body.html [ Skip ]
 crbug.com/308768 http/tests/security/XFrameOptions/x-frame-options-deny-meta-tag-parent-same-origin-deny.html [ Skip ]