Chain.terse shouldn't return an empty chain.

pkg/stack_trace/test/chain_test.dart

Index: pkg/stack_trace/test/chain_test.dart
diff --git a/pkg/stack_trace/test/chain_test.dart b/pkg/stack_trace/test/chain_test.dart
index 4d31acbb47f1964a2407a51d6dc23153042fb943..9c166909e1f65f741a0d774bb445d28ffe7ed355 100644
--- a/pkg/stack_trace/test/chain_test.dart
+++ b/pkg/stack_trace/test/chain_test.dart
@@ -386,6 +386,21 @@ void main() {
           '$userSlashCode 10:11  Foo.bar\n'
           'dart:core             Bar.baz\n'));
     });
+
+    test("doesn't return in an empty chain", () {
+      var chain = new Chain([
+        new Trace.parse(
+            'dart:core 10:11                             Foo.bar\n'
+            'package:stack_trace/stack_trace.dart 10:11  Bar.baz\n'
+            'dart:core 10:11                             Zip.zap'),
+        new Trace.parse(
+            'dart:core 10:11                             A.b\n'
+            'package:stack_trace/stack_trace.dart 10:11  C.d\n'
+            'dart:core 10:11                             E.f')
+      ]);
+
+      expect(chain.terse.toString(), equals('dart:core  E.f\n'));
+    });
   });
 
   test('Chain.toTrace eliminates asynchronous gaps', () {