Always adjust amount of external memory when change is reported.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 7a838d81030d12d2cb135f964071784424c56ecc..3a5b60d0820f029e05ba3fc9b978dde5713efde8 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -7309,9 +7309,8 @@ int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
       amount - *amount_of_external_allocated_memory_at_last_global_gc >
           I::kExternalAllocationLimit) {
     CollectAllGarbage("external memory allocation limit reached.");
-  } else {
-    *amount_of_external_allocated_memory = amount;
   }
+  *amount_of_external_allocated_memory = amount;
   return *amount_of_external_allocated_memory;
 }