Revert "[kernel] Stream everything. Replace .kernel_function with .kernel_offset"

runtime/vm/raw_object_snapshot.cc

Index: runtime/vm/raw_object_snapshot.cc
diff --git a/runtime/vm/raw_object_snapshot.cc b/runtime/vm/raw_object_snapshot.cc
index 6317a72d021a1dc720ef162d66fb573b14c61a2a..c6104313fbb4c9206b97de56f934ab0fe073d7a9 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -757,7 +757,7 @@ RawFunction* Function::ReadFrom(SnapshotReader* reader,
     func.set_deoptimization_counter(reader->Read<int8_t>());
     func.set_optimized_instruction_count(reader->Read<uint16_t>());
     func.set_optimized_call_site_count(reader->Read<uint16_t>());
-    func.set_kernel_offset(0);
+    func.set_kernel_function(NULL);
     func.set_was_compiled(false);
 
     // Set all the object fields.
@@ -863,7 +863,7 @@ RawField* Field::ReadFrom(SnapshotReader* reader,
   field.set_guarded_cid(reader->Read<int32_t>());
   field.set_is_nullable(reader->Read<int32_t>());
   field.set_kind_bits(reader->Read<uint8_t>());
-  field.set_kernel_offset(0);
+  field.set_kernel_field(NULL);
 
   // Set all the object fields.
   READ_OBJECT_FIELDS(field, field.raw()->from(), field.raw()->to_snapshot(kind),