Use List<String> for combinators in summaries.

pkg/analyzer/lib/src/summary/summarize_elements.dart

Index: pkg/analyzer/lib/src/summary/summarize_elements.dart
diff --git a/pkg/analyzer/lib/src/summary/summarize_elements.dart b/pkg/analyzer/lib/src/summary/summarize_elements.dart
index bf8a20170ed8b2fe6cbded875eea1a674c0a58da..e3d0253f72cc55e57313dcea506200beafa2a242 100644
--- a/pkg/analyzer/lib/src/summary/summarize_elements.dart
+++ b/pkg/analyzer/lib/src/summary/summarize_elements.dart
@@ -342,21 +342,14 @@ class _LibrarySerializer {
       NamespaceCombinator combinator) {
     UnlinkedCombinatorBuilder b = new UnlinkedCombinatorBuilder(ctx);
     if (combinator is ShowElementCombinator) {
-      b.shows = combinator.shownNames.map(serializeCombinatorName).toList();
+      b.shows = combinator.shownNames;
     } else if (combinator is HideElementCombinator) {
-      b.hides = combinator.hiddenNames.map(serializeCombinatorName).toList();
+      b.hides = combinator.hiddenNames;
     }
     return b;
   }
 
   /**
-   * Serialize the given [name] into an [UnlinkedCombinatorName].
-   */
-  UnlinkedCombinatorNameBuilder serializeCombinatorName(String name) {
-    return encodeUnlinkedCombinatorName(ctx, name: name);
-  }
-
-  /**
    * Return the index of the entry in the dependency table
    * ([PrelinkedLibrary.dependencies]) for the given [dependentLibrary].  A new
    * entry is added to the table if necessary to satisfy the request.