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

src/ia32/builtins-ia32.cc

Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index 827a4c4f43656a31a225bdc8476cddbcbe82fddf..5821b855c33f4b6b7c0d2ab64f658279e8d79363 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -32,6 +32,12 @@ void Builtins::Generate_Adaptor(MacroAssembler* masm,
   // -----------------------------------
   __ 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) {