Fix asserts in StackFrameIterator which were effectively disabled

runtime/lib/stacktrace.cc

Index: runtime/lib/stacktrace.cc
diff --git a/runtime/lib/stacktrace.cc b/runtime/lib/stacktrace.cc
index daf703697e833d29caf0ce4d54e296a27a1c865f..48b87d4c50d5402a8ac8f4bc8d19b80cbab7eac6 100644
--- a/runtime/lib/stacktrace.cc
+++ b/runtime/lib/stacktrace.cc
@@ -141,7 +141,9 @@ DEFINE_NATIVE_ENTRY(StackTrace_setAsyncThreadStackTrace, 1) {
 static void AppendFrames(const GrowableObjectArray& code_list,
                          const GrowableObjectArray& pc_offset_list,
                          int skip_frames) {
-  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames,
+                            Thread::Current(),
+                            StackFrameIterator::kNoCrossThreadIteration);
   StackFrame* frame = frames.NextFrame();
   ASSERT(frame != NULL);  // We expect to find a dart invocation frame.
   Code& code = Code::Handle();
@@ -193,7 +195,9 @@ void _printCurrentStackTrace() {
 
 // Like _printCurrentStackTrace, but works in a NoSafepointScope.
 void _printCurrentStackTraceNoSafepoint() {
-  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames);
+  StackFrameIterator frames(StackFrameIterator::kDontValidateFrames,
+                            Thread::Current(),
+                            StackFrameIterator::kNoCrossThreadIteration);
   StackFrame* frame = frames.NextFrame();
   while (frame != NULL) {
     OS::PrintErr("%s\n", frame->ToCString());