[csa] Add CSA::CallBuiltin and Builtins::CallableFor

src/callable.h

+// Copyright 2017 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.
+
+#ifndef V8_CALLABLE_H_
+#define V8_CALLABLE_H_
+
+#include "src/allocation.h"
+#include "src/interface-descriptors.h"
+
+namespace v8 {
+namespace internal {
+
+class Code;
+
+// Associates a body of code with an interface descriptor.
+class Callable final BASE_EMBEDDED {
+ public:
+  Callable(Handle<Code> code, CallInterfaceDescriptor descriptor)
+      : code_(code), descriptor_(descriptor) {}
+
+  Handle<Code> code() const { return code_; }
+  CallInterfaceDescriptor descriptor() const { return descriptor_; }
+
+ private:
+  const Handle<Code> code_;
+  const CallInterfaceDescriptor descriptor_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_CALLABLE_H_