Completely remove InterruptableThreadState and Fix ThreadRegistry leak

runtime/vm/thread_registry.h

 // 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.
 
 #ifndef VM_THREAD_REGISTRY_H_
 #define VM_THREAD_REGISTRY_H_
 
 #include "vm/globals.h"
 #include "vm/growable_array.h"
 #include "vm/isolate.h"
@@ skipping 120 matching lines @@
       StackFrameIterator frames_iterator(state.top_exit_frame_info,
                                          validate_frames);
       StackFrame* frame = frames_iterator.NextFrame();
       while (frame != NULL) {
         frame->VisitObjectPointers(visitor);
         frame = frames_iterator.NextFrame();
       }
     }
   }
 
- private:
+  void PruneThread(Thread* thread);
+
   struct Entry {
     // NOTE: |thread| is deleted automatically when the thread exits.
     // In other words, it is not safe to dereference |thread| unless you are on
     // the thread itself.
     Thread* thread;
     bool scheduled;
     Thread::State state;
   };
 
+  class EntryIterator {
+   public:
+    explicit EntryIterator(ThreadRegistry* registry);
+    ~EntryIterator();
+
+    // Returns false when there are no more entries.
+    bool HasNext() const;
+
+    // Returns the next entry and moves forward.
+    const Entry& Next();
+
+   private:
+    void Reset(ThreadRegistry* registry);
+
+    intptr_t index_;
+    ThreadRegistry* registry_;
+  };
+
+ private:
   // Returns Entry corresponding to thread in registry or NULL.
   // Note: Lock should be taken before this function is called.
   // TODO(koda): Add method Monitor::IsOwnedByCurrentThread.
   Entry* FindEntry(Thread* thread) {
     for (int i = 0; i < entries_.length(); ++i) {
       if (entries_[i].thread == thread) {
         return &entries_[i];
       }
     }
     return NULL;
@@ skipping 14 matching lines @@
   intptr_t remaining_;    // Number of threads yet to reach their safepoint.
   int64_t round_;         // Counter, to prevent missing updates to remaining_
                           // (see comments in CheckSafepointLocked).
 
   DISALLOW_COPY_AND_ASSIGN(ThreadRegistry);
 };
 
 }  // namespace dart
 
 #endif  // VM_THREAD_REGISTRY_H_