Remove 'serializeLibrary(LibraryElement)' and its tests.

pkg/analyzer/test/src/summary/summarize_ast_test.dart

Index: pkg/analyzer/test/src/summary/summarize_ast_test.dart
diff --git a/pkg/analyzer/test/src/summary/summarize_ast_test.dart b/pkg/analyzer/test/src/summary/summarize_ast_test.dart
index 87fb3493d99745d6ac11bb3bc18e79f250764fa0..b0c346f5f38ba52c6d237a43ada87f773c1588ec 100644
--- a/pkg/analyzer/test/src/summary/summarize_ast_test.dart
+++ b/pkg/analyzer/test/src/summary/summarize_ast_test.dart
@@ -137,6 +137,8 @@ abstract class LinkedSummarizeAstTest extends SummaryLinkerTest
   @override
   List<UnlinkedUnit> unlinkedUnits;
 
+  LinkerInputs linkerInputs;
+
   @override
   bool get checkAstDerivedData => true;
 
@@ -152,7 +154,7 @@ abstract class LinkedSummarizeAstTest extends SummaryLinkerTest
   @override
   void serializeLibraryText(String text, {bool allowErrors: false}) {
     Map<String, UnlinkedUnitBuilder> uriToUnit = this._filesToLink.uriToUnit;
-    LinkerInputs linkerInputs = createLinkerInputs(text);
+    linkerInputs = createLinkerInputs(text);
     linked = link(
         linkerInputs.linkedLibraries,
         linkerInputs.getDependency,