[builtins] Fix context for ConstructStub calls into C++.

src/x64/builtins-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 13 matching lines @@
   //  -- rdi                 : target
   //  -- rdx                 : new.target
   //  -- rsp[0]              : return address
   //  -- rsp[8]              : last argument
   //  -- ...
   //  -- rsp[8 * argc]       : first argument
   //  -- rsp[8 * (argc + 1)] : receiver
   // -----------------------------------
   __ AssertFunction(rdi);
 
+  // Make sure we operate in the context of the called function (for example
+  // ConstructStubs implemented in C++ will be run in the context of the caller
+  // instead of the callee, due to the way that [[Construct]] is defined for
+  // ordinary functions).
+  __ movp(rsi, FieldOperand(rdi, JSFunction::kContextOffset));
+
   // Insert extra arguments.
   int num_extra_args = 0;
   if (extra_args != BuiltinExtraArguments::kNone) {
     __ PopReturnAddressTo(kScratchRegister);
     if (extra_args & BuiltinExtraArguments::kTarget) {
       ++num_extra_args;
       __ Push(rdi);
     }
     if (extra_args & BuiltinExtraArguments::kNewTarget) {
       ++num_extra_args;
@@ skipping 2401 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64