Make FastNewFunctionContextStub take slots parameter

src/full-codegen/x64/full-codegen-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/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 157 matching lines @@
       __ CallRuntime(Runtime::kNewScriptContext);
       PrepareForBailoutForId(BailoutId::ScriptContext(),
                              BailoutState::TOS_REGISTER);
       // The new target value is not used, clobbering is safe.
       DCHECK_NULL(info->scope()->new_target_var());
     } else {
       if (info->scope()->new_target_var() != nullptr) {
         __ Push(rdx);  // Preserve new target.
       }
       if (slots <= FastNewFunctionContextStub::kMaximumSlots) {
-        FastNewFunctionContextStub stub(isolate(), slots);
+        FastNewFunctionContextStub stub(isolate());
+        __ Set(FastNewFunctionContextDescriptor::SlotsRegister(), slots);
         __ CallStub(&stub);
         // Result of FastNewFunctionContextStub is always in new space.
         need_write_barrier = false;
       } else {
         __ Push(rdi);
         __ CallRuntime(Runtime::kNewFunctionContext);
       }
       if (info->scope()->new_target_var() != nullptr) {
         __ Pop(rdx);  // Restore new target.
       }
@@ skipping 3473 matching lines @@
   DCHECK_EQ(
       isolate->builtins()->OnStackReplacement()->entry(),
       Assembler::target_address_at(call_target_address, unoptimized_code));
   return ON_STACK_REPLACEMENT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64