Add support for forceful termination of JavaScript execution.

src/v8threads.h

Index: src/v8threads.h
===================================================================
--- src/v8threads.h	(revision 2717)
+++ src/v8threads.h	(working copy)
@@ -50,6 +50,12 @@
   void set_id(int id) { id_ = id; }
   int id() { return id_; }
 
+  // Should the thread be terminated when it is restored?
+  bool terminate_on_restore() { return terminate_on_restore_; }
+  void set_terminate_on_restore(bool terminate_on_restore) {
+    terminate_on_restore_ = terminate_on_restore;
+  }
+
   // Get data area for archiving a thread.
   char* data() { return data_; }
  private:
@@ -58,6 +64,7 @@
   void AllocateSpace();
 
   int id_;
+  bool terminate_on_restore_;
   char* data_;
   ThreadState* next_;
   ThreadState* previous_;
@@ -88,6 +95,8 @@
   static int CurrentId();
   static void AssignId();
 
+  static void TerminateExecution(int thread_id);
+
   static const int kInvalidId = -1;
  private:
   static void EagerlyArchiveThread();