Make stack_parameter_count a plain register.

src/ia32/deoptimizer-ia32.cc

Index: src/ia32/deoptimizer-ia32.cc
diff --git a/src/ia32/deoptimizer-ia32.cc b/src/ia32/deoptimizer-ia32.cc
index bb32bc5068694569e0952599f530c50f5e88fcb9..871068ca01d400d34cbe68270788c07861886cf5 100644
--- a/src/ia32/deoptimizer-ia32.cc
+++ b/src/ia32/deoptimizer-ia32.cc
@@ -202,10 +202,7 @@ void Deoptimizer::SetPlatformCompiledStubRegisters(
     FrameDescription* output_frame, CodeStubInterfaceDescriptor* descriptor) {
   intptr_t handler =
       reinterpret_cast<intptr_t>(descriptor->deoptimization_handler_);
-  int params = descriptor->register_param_count_;
-  if (descriptor->stack_parameter_count_ != NULL) {
-    params++;
-  }
+  int params = descriptor->environment_length();
   output_frame->SetRegister(eax.code(), params);
   output_frame->SetRegister(ebx.code(), handler);
 }