Set the current context to the function's context when entering to LAP.

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 9c70fe6c8d8c833422ea5d9f7435fe9ddf537e45..1d7ee71cafcc3ded90039e69f07026a167e5da1e 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -2711,6 +2711,7 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   //  -- ...
   //  -- rsp[argc * 8]       : first argument
   //  -- rsp[(argc + 1) * 8] : receiver
+  //  -- rsp[(argc + 2) * 8] : accessor_holder
   // -----------------------------------
 
   Register callee = rdi;
@@ -2757,15 +2758,25 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   // holder
   __ Push(holder);
 
-  __ movp(scratch, rsp);
-  // Push return address back on stack.
-  __ PushReturnAddressFrom(return_address);
-
-  if (!this->is_lazy()) {
+  // enter a new context
+  int argc = this->argc();
+  if (this->is_lazy()) {
+    // load context from accessor_holder
+    Register accessor_holder = context;
+    __ movp(accessor_holder,
+            MemOperand(rsp, (argc + FCA::kArgsLength + 1) * kPointerSize));
+    __ movp(scratch, FieldOperand(accessor_holder, HeapObject::kMapOffset));
+    __ GetMapConstructor(scratch, scratch, context);
+    __ movp(context, FieldOperand(scratch, JSFunction::kContextOffset));
+  } else {
     // load context from callee
     __ movp(context, FieldOperand(callee, JSFunction::kContextOffset));
   }
 
+  __ movp(scratch, rsp);
+  // Push return address back on stack.
+  __ PushReturnAddressFrom(return_address);
+
   // Allocate the v8::Arguments structure in the arguments' space since
   // it's not controlled by GC.
   const int kApiStackSpace = 3;
@@ -2773,7 +2784,6 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   PrepareCallApiFunction(masm, kApiStackSpace);
 
   // FunctionCallbackInfo::implicit_args_.
-  int argc = this->argc();
   __ movp(StackSpaceOperand(0), scratch);
   __ addp(scratch, Immediate((argc + FCA::kArgsLength - 1) * kPointerSize));
   // FunctionCallbackInfo::values_.