Fix call stack sampling for the case when native callback invokes JS function

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 6e5d5c674a4a95328b93684e3105d6f6bb5f3f84..26122424647e2df352a6682c0f8eb32f7e5030a0 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -65,6 +65,7 @@ class CpuProfiler;
 class DeoptimizerData;
 class Deserializer;
 class EmptyStatement;
+class ExternalCallbackScope;
 class ExternalReferenceTable;
 class Factory;
 class FunctionInfoListener;
@@ -279,7 +280,8 @@ class ThreadLocalTop BASE_EMBEDDED {
 #endif  // USE_SIMULATOR
 
   Address js_entry_sp_;  // the stack pointer of the bottom JS entry frame
-  Address external_callback_;  // the external callback we're currently in
+  // the external callback we're currently in
+  ExternalCallbackScope* external_callback_scope_;
   StateTag current_vm_state_;
 
   // Generated code scratch locations.
@@ -1032,11 +1034,11 @@ class Isolate {
 
   static const int kJSRegexpStaticOffsetsVectorSize = 128;
 
-  Address external_callback() {
-    return thread_local_top_.external_callback_;
+  ExternalCallbackScope* external_callback_scope() {
+    return thread_local_top_.external_callback_scope_;
   }
-  void set_external_callback(Address callback) {
-    thread_local_top_.external_callback_ = callback;
+  void set_external_callback_scope(ExternalCallbackScope* scope) {
+    thread_local_top_.external_callback_scope_ = scope;
   }
 
   StateTag current_vm_state() {