[promisehook] Add is_promisehook_enabled

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 6f45e63e4a82dcb78f504dcec8a72772d29f6510..eca069c576ae009c9772acfe2a70ad65446b0d45 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1123,6 +1123,13 @@ class Isolate {
   int GetNextUniqueSharedFunctionInfoId() { return next_unique_sfi_id_++; }
 #endif
 
+  Address is_promisehook_enabled_address() {
+    return reinterpret_cast<Address>(&is_promisehook_enabled_);
+  }
+  bool IsPromiseHookEnabled() { return is_promisehook_enabled_; }
+  void EnablePromiseHook();
+  void DisablePromiseHook();
+
   // Support for dynamically disabling tail call elimination.
   Address is_tail_call_elimination_enabled_address() {
     return reinterpret_cast<Address>(&is_tail_call_elimination_enabled_);
@@ -1363,6 +1370,9 @@ class Isolate {
   // True if this isolate was initialized from a snapshot.
   bool initialized_from_snapshot_;
 
+  // True if PromiseHook feature is enabled.
+  bool is_promisehook_enabled_;
+
   // True if ES2015 tail call elimination feature is enabled.
   bool is_tail_call_elimination_enabled_;