Tweak the TurboFan pipeline for stub compilation.

src/compiler.h

Index: src/compiler.h
diff --git a/src/compiler.h b/src/compiler.h
index 630e9cb74e47343efc66ed4c75894cebf792f762..56bbf3778d8f0a75c90c4f6ca70f880abcf6d377 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -163,6 +163,7 @@ class CompilationInfo {
   int num_parameters() const;
   int num_heap_slots() const;
   Code::Flags flags() const;
+  bool has_scope() const { return scope() != nullptr; }
 
   void set_parameter_count(int parameter_count) {
     DCHECK(IsStub());
@@ -270,6 +271,11 @@ class CompilationInfo {
     optimization_id_ = isolate()->NextOptimizationId();
   }
 
+  void SetStub(CodeStub* code_stub) {
+    SetMode(STUB);
+    code_stub_ = code_stub;
+  }
+
   // Deoptimization support.
   bool HasDeoptimizationSupport() const {
     return GetFlag(kDeoptimizationSupport);