Allow implicit 'close your eyes' of native methods. This will hopefully fix issue 3466.

vm/intermediate_language_x64.cc

Index: vm/intermediate_language_x64.cc
===================================================================
--- vm/intermediate_language_x64.cc	(revision 8752)
+++ vm/intermediate_language_x64.cc	(working copy)
@@ -578,14 +578,18 @@
   // Push the result place holder initialized to NULL.
   __ PushObject(Object::ZoneHandle());
   // Pass a pointer to the first argument in RAX.
-  if (!has_optional_parameters()) {
-    __ leaq(RAX, Address(RBP, (1 + argument_count()) * kWordSize));
+  intptr_t arg_count = argument_count();
+  if (is_native_instance_closure()) {
+    arg_count += 1;
+  }
+  if (!has_optional_parameters() && !is_native_instance_closure()) {
+    __ leaq(RAX, Address(RBP, (1 + arg_count) * kWordSize));
   } else {
     __ leaq(RAX,
             Address(RBP, ParsedFunction::kFirstLocalSlotIndex * kWordSize));
   }
   __ movq(RBX, Immediate(reinterpret_cast<uword>(native_c_function())));
-  __ movq(R10, Immediate(argument_count()));
+  __ movq(R10, Immediate(arg_count));
   compiler->GenerateCall(token_index(),
                          try_index(),
                          &StubCode::CallNativeCFunctionLabel(),