Add instruction tags to saved ICData (debug mode only).

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 e8fcf69a2f044ac590e51f3e12dafd0929b68fad..cf81ac6c6b78111cf482e6fa6c7a1dbf101e0a0e 100644
--- a/runtime/vm/raw_object_snapshot.cc
+++ b/runtime/vm/raw_object_snapshot.cc
@@ -1972,6 +1972,9 @@ RawICData* ICData::ReadFrom(SnapshotReader* reader,
 
   result.set_deopt_id(reader->Read<int32_t>());
   result.set_state_bits(reader->Read<uint32_t>());
+#if defined(TAG_IC_DATA)
+  result.set_tag(reader->Read<int16_t>());
+#endif
 
   // Set all the object fields.
   RawObject** toobj = reader->snapshot_code()
@@ -2004,6 +2007,9 @@ void RawICData::WriteTo(SnapshotWriter* writer,
   // Write out all the non object fields.
   writer->Write<int32_t>(ptr()->deopt_id_);
   writer->Write<uint32_t>(ptr()->state_bits_);
+#if defined(TAG_IC_DATA)
+  writer->Write<int16_t>(ptr()->tag_);
+#endif
 
   // Write out all the object pointer fields.
   // In precompiled snapshots, omit the owner field. The owner field may