Reserve element 0 in the references table for `dynamic`.

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

Index: pkg/analyzer/test/src/summary/summary_test.dart
diff --git a/pkg/analyzer/test/src/summary/summary_test.dart b/pkg/analyzer/test/src/summary/summary_test.dart
index c28ae72e9460f68e1091361103abf01893e9d7db..3646f3294de7f271697df8547ac4a55548e8e5cb 100644
--- a/pkg/analyzer/test/src/summary/summary_test.dart
+++ b/pkg/analyzer/test/src/summary/summary_test.dart
@@ -228,6 +228,11 @@ abstract class SummaryTest {
     int index = typeRef.reference;
     UnlinkedReference reference = sourceUnit.unlinked.references[index];
     PrelinkedReference referenceResolution = sourceUnit.references[index];
+    if (index == 0) {
+      // Index 0 is reserved for "dynamic".
+      expect(reference.name, isEmpty);
+      expect(reference.prefix, 0);
+    }
     if (absoluteUri == null) {
       expect(referenceResolution.dependency, 0);
     } else {