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

src/x87/builtins-x87.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_X87
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 14 matching lines @@
   //  -- edi                : target
   //  -- edx                : new.target
   //  -- esp[0]             : return address
   //  -- esp[4]             : last argument
   //  -- ...
   //  -- esp[4 * argc]      : first argument
   //  -- esp[4 * (argc +1)] : receiver
   // -----------------------------------
   __ AssertFunction(edi);
 
+  // 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).
+  __ mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
+
   // Insert extra arguments.
   int num_extra_args = 0;
   if (extra_args != BuiltinExtraArguments::kNone) {
     __ PopReturnAddressTo(ecx);
     if (extra_args & BuiltinExtraArguments::kTarget) {
       ++num_extra_args;
       __ Push(edi);
     }
     if (extra_args & BuiltinExtraArguments::kNewTarget) {
       ++num_extra_args;
@@ skipping 2328 matching lines @@
 
   __ bind(&ok);
   __ ret(0);
 }
 
 #undef __
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87