Remove obsolete global V8::IsRunning() predicate.

src/v8.h

Index: src/v8.h
diff --git a/src/v8.h b/src/v8.h
index aee4890aa066a9a949346d522b3106174fba9ae3..abace93f35e57c95344fa9c2aa70d5d440229fdd 100644
--- a/src/v8.h
+++ b/src/v8.h
@@ -82,7 +82,6 @@ class V8 : public AllStatic {
   // empty heap.
   static bool Initialize(Deserializer* des);
   static void TearDown();
-  static bool IsRunning() { return is_running_; }
   // To be dead you have to have lived
   // TODO(isolates): move IsDead to Isolate.
   static bool IsDead() { return has_fatal_error_ || has_been_disposed_; }
@@ -130,8 +129,6 @@ class V8 : public AllStatic {
   static void InitializeOncePerProcessImpl();
   static void InitializeOncePerProcess();
 
-  // True if engine is currently running
-  static bool is_running_;
   // True if V8 has ever been run
   static bool has_been_set_up_;
   // True if error has been signaled for current engine