Add metadata annotations to library definitions.

pkg/kernel/binary.md

Index: pkg/kernel/binary.md
diff --git a/pkg/kernel/binary.md b/pkg/kernel/binary.md
index 22215fbaebdbea50572a19aef606e2fac0ea59c3..2815c23dc69c43e14962533ff2ab6e49fa58acdc 100644
--- a/pkg/kernel/binary.md
+++ b/pkg/kernel/binary.md
@@ -166,6 +166,7 @@ type Library {
   StringReference name;
   // An absolute path URI to the .dart file from which the library was created.
   UriReference fileUri;
+  List<Expression> annotations;
   List<LibraryDependency> libraryDependencies;
   List<Class> classes;
   List<Field> fields;