Simplify pending message object handling.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index e8c2a711ed81ccf9fe8d80abc484179f4e6b3fe4..5c179f1aa93dcfa019b47a4220b6f90036ee86fe 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -282,7 +282,6 @@ class ThreadLocalTop BASE_EMBEDDED {
   Address pending_handler_sp_;
 
   // Communication channel between Isolate::Throw and message consumers.
-  bool has_pending_message_;
   bool rethrowing_message_;
   Object* pending_message_obj_;
 
@@ -604,7 +603,6 @@ class Isolate {
   THREAD_LOCAL_TOP_ACCESSOR(bool, external_caught_exception)
 
   void clear_pending_message() {
-    thread_local_top_.has_pending_message_ = false;
     thread_local_top_.pending_message_obj_ = heap_.the_hole_value();
   }
   v8::TryCatch* try_catch_handler() {
@@ -623,10 +621,6 @@ class Isolate {
     return reinterpret_cast<Address>(&thread_local_top_.pending_message_obj_);
   }
 
-  Address has_pending_message_address() {
-    return reinterpret_cast<Address>(&thread_local_top_.has_pending_message_);
-  }
-
   Object* scheduled_exception() {
     DCHECK(has_scheduled_exception());
     DCHECK(!thread_local_top_.scheduled_exception_->IsException());