Build summary2 in DDC only when it is fully enabled.

R=brianwilkerson@google.com, paulberry@google.com

Change-Id: I3bbfbc743e7e1e6908cf2bed465fb844a70fe78d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106944
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
diff --git a/pkg/analyzer/lib/src/dart/analysis/ddc.dart b/pkg/analyzer/lib/src/dart/analysis/ddc.dart
index 9a37007..0426f4a 100644
--- a/pkg/analyzer/lib/src/dart/analysis/ddc.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/ddc.dart
@@ -6,6 +6,7 @@
 
 import 'package:analyzer/dart/analysis/declared_variables.dart';
 import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/dart/analysis/restricted_analysis_context.dart';
 import 'package:analyzer/src/dart/analysis/session.dart';
@@ -96,8 +97,11 @@
   }
 
   void _buildPackageBundleBytes() {
-    _computeLinkedLibraries1();
-    _computeLinkedLibraries2();
+    if (AnalysisDriver.useSummary2) {
+      _computeLinkedLibraries2();
+    } else {
+      _computeLinkedLibraries1();
+    }
     summaryBytes = _assembler.assemble().toBuffer();
   }