Work around issue 14125 in stack_trace by adding a dummy setter.

pkg/stack_trace/lib/src/lazy_trace.dart

Index: pkg/stack_trace/lib/src/lazy_trace.dart
diff --git a/pkg/stack_trace/lib/src/lazy_trace.dart b/pkg/stack_trace/lib/src/lazy_trace.dart
index ae56b5fc3ae0239a591e7f1c62ac0b9733139936..7b0b251d91e531ed90d649f2a663ae5c8f393958 100644
--- a/pkg/stack_trace/lib/src/lazy_trace.dart
+++ b/pkg/stack_trace/lib/src/lazy_trace.dart
@@ -30,4 +30,7 @@ class LazyTrace implements Trace {
   Trace foldFrames(bool predicate(frame)) =>
     new LazyTrace(() => _trace.foldFrames(predicate));
   String toString() => _trace.toString();
+
+  // Work around issue 14125.
+  set frames(_) => throw new UnimplementedError();
 }