[turbofan] Mark dead JSInliner::Reduce as UNREACHABLE

This function is not used (anymore) but needs to be defined, so put an
UNREACHBLE inside.

Bug: v8:7790
Change-Id: I5a8df2cbc236f60ee95ccc9d91c288d8d9c19060
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1515792Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60188}

src/compiler/js-inlining.cc

@@ -370,11 +370,6 @@ void JSInliner::DetermineCallContext(
   UNREACHABLE();
 }
 
-Reduction JSInliner::Reduce(Node* node) {
-  if (!IrOpcode::IsInlineeOpcode(node->opcode())) return NoChange();
-  return ReduceJSCall(node);
-}
-
 Handle<Context> JSInliner::native_context() const {
   return handle(info_->native_context(), isolate());
 }

src/compiler/js-inlining.h

@@ -35,8 +35,7 @@ class JSInliner final : public AdvancedReducer {
 
   const char* reducer_name() const override { return "JSInliner"; }
 
-  // Reducer interface, eagerly inlines everything.
-  Reduction Reduce(Node* node) final;
+  Reduction Reduce(Node* node) final { UNREACHABLE(); }
 
   // Can be used by inlining heuristics or by testing code directly, without
   // using the above generic reducer interface of the inlining machinery.