Support tasks injection into a running VM.

include/v8-debug.h

Index: include/v8-debug.h
diff --git a/include/v8-debug.h b/include/v8-debug.h
index 6abf4e095bccadacdb6ef3fa4a3fc06fcbc76966..0505a01f921dd732bac7c8f3c936336fe47c93cd 100644
--- a/include/v8-debug.h
+++ b/include/v8-debug.h
@@ -177,6 +177,13 @@ class V8_EXPORT Debug {
   // stops.
   static void DebugBreakForCommand(Isolate* isolate, ClientData* data);
 
+  // Break execution of JavaScript in the given isolate (this method
+  // can be invoked from a non-VM thread) and execute the given task on the
+  // VM thread. The task is executed at most once and then gets deleted.
+  // If the task does not happen to execute for some reason, the task is
+  // deleted on the Isolate destruction.
+  static void BreakAndRun(Isolate* isolate, Task* task);
+
   // Message based interface. The message protocol is JSON.
   static void SetMessageHandler(MessageHandler handler);