Fix the 'Unused import' hint when using package summaries.

pkg/analyzer_cli/lib/src/package_analyzer.dart

Index: pkg/analyzer_cli/lib/src/package_analyzer.dart
diff --git a/pkg/analyzer_cli/lib/src/package_analyzer.dart b/pkg/analyzer_cli/lib/src/package_analyzer.dart
index b4563c3c047b2eeac81829a9dd99a4a021f39391..3373f6a08656bf16df161613f4d168071a2da20b 100644
--- a/pkg/analyzer_cli/lib/src/package_analyzer.dart
+++ b/pkg/analyzer_cli/lib/src/package_analyzer.dart
@@ -210,6 +210,9 @@ class InSummarySource extends Source {
   String get fullName => encoding;
 
   @override
+  int get hashCode => uri.hashCode;
+
+  @override
   bool get isInSystemLibrary => false;
 
   @override
@@ -222,6 +225,10 @@ class InSummarySource extends Source {
   UriKind get uriKind => UriKind.PACKAGE_URI;
 
   @override
+  bool operator ==(Object object) =>
+      object is InSummarySource && object.uri == uri;
+
+  @override
   bool exists() => true;
 
   @override