Emit API-only summaries

pkg/dev_compiler/lib/src/compiler/code_generator.dart

Index: pkg/dev_compiler/lib/src/compiler/code_generator.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/code_generator.dart b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
index 221d94ca9bdec9c773ecbd8bd8371ab22c711948..a4ab6156d39a8a8c18054e7615742f5bb23e7b4e 100644
--- a/pkg/dev_compiler/lib/src/compiler/code_generator.dart
+++ b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
@@ -217,7 +217,10 @@ class CodeGenerator extends GeneralizingAstVisitor
             true)
         .forEach(assembler.addLinkedLibrary);
 
-    return assembler.assemble().toBuffer();
+    var bundle = assembler.assemble();
+    // Preserve only API-level information in the summary.
+    bundle.flushInformative();
+    return bundle.toBuffer();
   }
 
   JS.Program _emitModule(List<CompilationUnit> compilationUnits) {