[turbofan] Separate JSInliningHeuristic into own class.

src/compiler/js-inlining-heuristic.h

+// Copyright 2015 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_COMPILER_JS_INLINING_HEURISTIC_H_
+#define V8_COMPILER_JS_INLINING_HEURISTIC_H_
+
+#include "src/compiler/js-inlining.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+class JSInliningHeuristic final : public AdvancedReducer {
+ public:
+  enum Mode { kRestrictedInlining, kGeneralInlining };
+  JSInliningHeuristic(Editor* editor, Mode mode, Zone* local_zone,
+                      CompilationInfo* info, JSGraph* jsgraph)
+      : AdvancedReducer(editor),
+        mode_(mode),
+        inliner_(editor, local_zone, info, jsgraph) {}
+
+  Reduction Reduce(Node* node) final;
+
+ private:
+  Mode const mode_;
+  JSInliner inliner_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_JS_INLINING_HEURISTIC_H_