Transform functions marked as async

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 0f6ecbb1976220ad249d2ac42d4f2a220d753070..82179e260ff29147213d6d7c12e04744c176acdb 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -1666,6 +1666,10 @@ class Function : public Object {
     return KindBits::decode(raw_ptr()->kind_tag_);
   }
 
+  RawFunction::Modifier modifier() const {
+    return ModifierBits::decode(raw_ptr()->kind_tag_);
+  }
+
   static const char* KindToCString(RawFunction::Kind kind);
 
   bool is_static() const { return StaticBit::decode(raw_ptr()->kind_tag_); }
@@ -1812,6 +1816,13 @@ class Function : public Object {
   void SetIsOptimizable(bool value) const;
   void SetIsNativeAutoSetupScope(bool value) const;
 
+  bool is_synthetic_container() const {
+    return SyntheticContainerBit::decode(raw_ptr()->kind_tag_);
+  }
+  void set_is_synthetic_container(bool value) const {
+    set_kind_tag(SyntheticContainerBit::update(value, raw_ptr()->kind_tag_));
+  }
+
   bool is_native() const { return NativeBit::decode(raw_ptr()->kind_tag_); }
   void set_is_native(bool value) const;
 
@@ -1962,6 +1973,11 @@ class Function : public Object {
     return kind() == RawFunction::kSignatureFunction;
   }
 
+
+  bool IsAsyncFunction() const {
+    return modifier() == RawFunction::kAsync;
+  }
+
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawFunction));
   }
@@ -2016,6 +2032,8 @@ class Function : public Object {
   static const int kCtorPhaseBody = 1 << 1;
   static const int kCtorPhaseAll = (kCtorPhaseInit | kCtorPhaseBody);
 
+  void set_modifier(RawFunction::Modifier value) const;
+
  private:
   void set_ic_data_array(const Array& value) const;
 
@@ -2034,6 +2052,8 @@ class Function : public Object {
     kRedirectingBit = 13,
     kExternalBit = 14,
     kAllowsHoistingCheckClassBit = 15,
+    kModifierPos = 16,
+    kSyntheticContainerBit = 18,
   };
   class KindBits :
     public BitField<RawFunction::Kind, kKindTagPos, kKindTagSize> {};  // NOLINT
@@ -2050,6 +2070,10 @@ class Function : public Object {
   class RedirectingBit : public BitField<bool, kRedirectingBit, 1> {};
   class AllowsHoistingCheckClassBit :
       public BitField<bool, kAllowsHoistingCheckClassBit, 1> {};  // NOLINT
+  class ModifierBits :
+    public BitField<RawFunction::Modifier, kModifierPos, 2> {};
+  class SyntheticContainerBit :
+    public BitField<bool, kSyntheticContainerBit, 1> {};
 
   void set_name(const String& value) const;
   void set_kind(RawFunction::Kind value) const;