VM: Make precompiler process constants/fields only once, avoid using pool.InfoAt()

runtime/vm/assembler.cc

Index: runtime/vm/assembler.cc
diff --git a/runtime/vm/assembler.cc b/runtime/vm/assembler.cc
index 4edcedd9fd1d150ce4d46ad90129d0bc438ed0c6..77d61b0de0f1fe4781cb471ed701123c1b849ea3 100644
--- a/runtime/vm/assembler.cc
+++ b/runtime/vm/assembler.cc
@@ -319,10 +319,10 @@ RawObjectPool* ObjectPoolWrapper::MakeObjectPool() {
     return Object::empty_object_pool().raw();
   }
   const ObjectPool& result = ObjectPool::Handle(ObjectPool::New(len));
-  const TypedData& info_array = TypedData::Handle(result.info_array());
+  ObjectPoolInfo pool_info(result);
   for (intptr_t i = 0; i < len; ++i) {
     ObjectPool::EntryType info = object_pool_[i].type_;
-    info_array.SetInt8(i, static_cast<int8_t>(info));
+    pool_info.SetInfoAt(i, info);
     if (info == ObjectPool::kTaggedObject) {
       result.SetObjectAt(i, *object_pool_[i].obj_);
     } else {