Fix asserts in StackFrameIterator which were effectively disabled

runtime/vm/stack_trace.cc

Index: runtime/vm/stack_trace.cc
diff --git a/runtime/vm/stack_trace.cc b/runtime/vm/stack_trace.cc
index c746d50104a00f6836daa4ffbaefa83c7f2f1706..e0c77177b2013d97187f3fc0d042c4272ba494c6 100644
--- a/runtime/vm/stack_trace.cc
+++ b/runtime/vm/stack_trace.cc
@@ -13,7 +13,8 @@ intptr_t StackTraceUtils::CountFrames(Thread* thread,
                                       const Function& async_function) {
   Zone* zone = thread->zone();
   intptr_t frame_count = 0;
-  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames, thread,
+                            StackFrameIterator::kNoCrossThreadIteration);
   StackFrame* frame = frames.NextFrame();
   ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
   Code& code = Code::Handle(zone);
@@ -48,7 +49,8 @@ intptr_t StackTraceUtils::CollectFrames(Thread* thread,
                                         intptr_t count,
                                         int skip_frames) {
   Zone* zone = thread->zone();
-  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames, thread,
+                            StackFrameIterator::kNoCrossThreadIteration);
   StackFrame* frame = frames.NextFrame();
   ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
   Function& function = Function::Handle(zone);