Restructure/fix thread pointer visiting; added some asserts.

runtime/vm/thread_registry.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/thread_registry.h"
 
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 
 namespace dart {
@@ skipping 38 matching lines @@
   AddToActiveListLocked(thread);
   return thread;
 }
 
 
 void ThreadRegistry::ReturnThreadLocked(bool is_mutator, Thread* thread) {
   ASSERT(threads_lock()->IsOwnedByCurrentThread());
   // Remove thread from the active list for the isolate.
   RemoveFromActiveListLocked(thread);
   if (!is_mutator) {
-    ASSERT(thread->api_top_scope() == NULL);
     ReturnToFreelistLocked(thread);
   }
 }
 
 
 void ThreadRegistry::VisitObjectPointers(ObjectPointerVisitor* visitor,
                                          bool validate_frames) {
   MonitorLocker ml(threads_lock());
   bool mutator_thread_visited = false;
   Thread* thread = active_list_;
   while (thread != NULL) {
-    if (thread->zone() != NULL) {
-      thread->zone()->VisitObjectPointers(visitor);
-    }
-    thread->VisitObjectPointers(visitor);
+    thread->VisitObjectPointers(visitor, validate_frames);
     if (mutator_thread_ == thread) {
       mutator_thread_visited = true;
     }
-    // Iterate over all the stack frames and visit objects on the stack.
-    StackFrameIterator frames_iterator(thread->top_exit_frame_info(),
-                                       validate_frames);
-    StackFrame* frame = frames_iterator.NextFrame();
-    while (frame != NULL) {
-      frame->VisitObjectPointers(visitor);
-      frame = frames_iterator.NextFrame();
-    }
     thread = thread->next_;
   }
   // Visit mutator thread even if it is not in the active list because of
   // api handles.
   if (!mutator_thread_visited && (mutator_thread_ != NULL)) {
-    mutator_thread_->VisitObjectPointers(visitor);
+    mutator_thread_->VisitObjectPointers(visitor, validate_frames);
   }
 }
 
 
 void ThreadRegistry::PrepareForGC() {
   MonitorLocker ml(threads_lock());
   Thread* thread = active_list_;
   while (thread != NULL) {
     thread->PrepareForGC();
     thread = thread->next_;
@@ skipping 47 matching lines @@
   ASSERT(thread->os_thread_ == NULL);
   ASSERT(thread->isolate_ == NULL);
   ASSERT(thread->heap_ == NULL);
   ASSERT(threads_lock()->IsOwnedByCurrentThread());
   // Add thread to the free list.
   thread->next_ = free_list_;
   free_list_ = thread;
 }
 
 }  // namespace dart