[turbofan] Separate JSInliningHeuristic into own class.

src/compiler/js-inlining-heuristic.cc

+// 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.
+
+#include "src/compiler/js-inlining-heuristic.h"
+
+#include "src/compiler/node-matchers.h"
+#include "src/objects-inl.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+Reduction JSInliningHeuristic::Reduce(Node* node) {
+  if (node->opcode() != IrOpcode::kJSCallFunction) return NoChange();
+
+  Node* callee = node->InputAt(0);
+  HeapObjectMatcher match(callee);
+  if (!match.HasValue() || !match.Value()->IsJSFunction()) return NoChange();
+  Handle<JSFunction> function = Handle<JSFunction>::cast(match.Value());
+
+  // Functions marked with %SetForceInlineFlag are immediately inlined.
+  if (function->shared()->force_inline()) {
+    return inliner_.ReduceJSCallFunction(node, function);
+  }
+
+  // All other functions are only handled with general inlining.
+  if (mode_ == kRestrictedInlining) return NoChange();
+  return inliner_.ReduceJSCallFunction(node, function);
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8