Record information about a summary's dependencies in the summary itself.

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

Index: pkg/analyzer/test/src/summary/linker_test.dart
diff --git a/pkg/analyzer/test/src/summary/linker_test.dart b/pkg/analyzer/test/src/summary/linker_test.dart
index 3be5a095830b9220e088a7882c753f5f644029d1..92a6fe97156c33d8848f0eb79bf26924b8085036 100644
--- a/pkg/analyzer/test/src/summary/linker_test.dart
+++ b/pkg/analyzer/test/src/summary/linker_test.dart
@@ -172,6 +172,9 @@ import "a.dart";
 var y = x;
 ''',
         path: '/b.dart');
+    expect(bundle2.dependencies, hasLength(1));
+    expect(bundle2.dependencies[0].summaryPath, '/a.ds');
+    expect(bundle2.dependencies[0].apiSignature, bundle1.apiSignature);
     addBundle('/a.ds', bundle1);
     addBundle('/b.ds', bundle2);
     createLinker('''