Hide synthetic metadata field exposed in r35926.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 7eee7301144974673bc71d31f26f867436d89c7b..068fd2a82f54ccd42ce9f8319ef657474984cfa3 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -2171,6 +2171,9 @@ class Field : public Object {
   bool is_static() const { return StaticBit::decode(raw_ptr()->kind_bits_); }
   bool is_final() const { return FinalBit::decode(raw_ptr()->kind_bits_); }
   bool is_const() const { return ConstBit::decode(raw_ptr()->kind_bits_); }
+  bool is_synthetic() const {
+    return SyntheticBit::decode(raw_ptr()->kind_bits_);
+  }
 
   inline intptr_t Offset() const;
   inline void SetOffset(intptr_t value_in_bytes) const;
@@ -2192,6 +2195,7 @@ class Field : public Object {
                        bool is_static,
                        bool is_final,
                        bool is_const,
+                       bool is_synthetic,
                        const Class& owner,
                        intptr_t token_pos);
 
@@ -2326,7 +2330,8 @@ class Field : public Object {
     kStaticBit,
     kFinalBit,
     kHasInitializerBit,
-    kUnboxingCandidateBit
+    kUnboxingCandidateBit,
+    kSyntheticBit
   };
   class ConstBit : public BitField<bool, kConstBit, 1> {};
   class StaticBit : public BitField<bool, kStaticBit, 1> {};
@@ -2335,6 +2340,7 @@ class Field : public Object {
   class UnboxingCandidateBit : public BitField<bool,
                                                kUnboxingCandidateBit, 1> {
   };
+  class SyntheticBit : public BitField<bool, kSyntheticBit, 1> {};
 
   // Update guarded cid and guarded length for this field. Returns true, if
   // deoptimization of dependent code is required.
@@ -2350,6 +2356,9 @@ class Field : public Object {
   void set_is_const(bool value) const {
     set_kind_bits(ConstBit::update(value, raw_ptr()->kind_bits_));
   }
+  void set_is_synthetic(bool value) const {
+    set_kind_bits(SyntheticBit::update(value, raw_ptr()->kind_bits_));
+  }
   void set_owner(const Object& value) const {
     StorePointer(&raw_ptr()->owner_, value.raw());
   }