[turbofan] Polymorphic inlining - try merge map check dispatch with function call dispatch.

This improves delta blue by about >5%. Unfortunately, this still does not help load
and check elimination because we do not learn maps from control flow.

Change-Id: I49a97dbc40576b9bc80c87ec2b459e37ba9b4440
Bug: v8:5267
Reviewed-on: https://chromium-review.googlesource.com/618328
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47405}

src/compiler/js-inlining-heuristic.h

@@ -64,6 +64,17 @@ class JSInliningHeuristic final : public AdvancedReducer {
   // Dumps candidates to console.
   void PrintCandidates();
   Reduction InlineCandidate(Candidate const& candidate, bool force_inline);
+  void CreateOrReuseDispatch(Node* node, Node* callee,
+                             Candidate const& candidate, Node** if_successes,
+                             Node** calls, Node** inputs, int input_count);
+  bool TryReuseDispatch(Node* node, Node* callee, Candidate const& candidate,
+                        Node** if_successes, Node** calls, Node** inputs,
+                        int input_count);
+  enum StateCloneMode { kCloneState, kChangeInPlace };
+  Node* DuplicateFrameStateAndRename(Node* frame_state, Node* from, Node* to,
+                                     StateCloneMode mode);
+  Node* DuplicateStateValuesAndRename(Node* state_values, Node* from, Node* to,
+                                      StateCloneMode mode);
 
   CommonOperatorBuilder* common() const;
   Graph* graph() const;