Start remove dependencies on compiler-related files.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 5eec794f4c87adbba3999b4cd9471014be3f029d..5b2beafd917a68348092b40a863985287600f6f3 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -2954,14 +2954,9 @@ class Field : public Object {
   const char* GuardedPropertiesAsCString() const;
 
   intptr_t UnboxedFieldCid() const {
-    ASSERT(IsUnboxedField());
     return guarded_cid();
   }
 
-  bool IsUnboxedField() const;
-
-  bool IsPotentialUnboxedField() const;
-
   bool is_unboxing_candidate() const {
     return UnboxingCandidateBit::decode(raw_ptr()->kind_bits_);
   }