Create summary files in MockSdk classes

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

Index: pkg/analyzer/test/src/summary/pub_summary_test.dart
diff --git a/pkg/analyzer/test/src/summary/pub_summary_test.dart b/pkg/analyzer/test/src/summary/pub_summary_test.dart
index 0724cef1914962d5c615fbb0e4d2e344f1df05a0..2d472799895217395a1a56a8c5393aa6c2999d15 100644
--- a/pkg/analyzer/test/src/summary/pub_summary_test.dart
+++ b/pkg/analyzer/test/src/summary/pub_summary_test.dart
@@ -254,7 +254,8 @@ A b;
     // Use DartSdk with a different API signature.
     // Different linked bundles should be created.
     {
-      MockSdk sdk = new MockSdk(resourceProvider: resourceProvider);
+      MockSdk sdk = new MockSdk(
+          buildSummaries: false, resourceProvider: resourceProvider);
       sdk.updateUriFile('dart:math', (String content) {
         return content + '  class NewMathClass {}';
       });