Background compilation work:

runtime/vm/flow_graph.h

Index: runtime/vm/flow_graph.h
diff --git a/runtime/vm/flow_graph.h b/runtime/vm/flow_graph.h
index d962f90fb9218a12f8524d805b77a5791e984677..cf62e82dde8dcb834b4dd0083252702b77355f89 100644
--- a/runtime/vm/flow_graph.h
+++ b/runtime/vm/flow_graph.h
@@ -279,6 +279,10 @@ class FlowGraph : public ZoneAllocated {
     return guarded_fields_;
   }
 
+  GrowableArray<const Field*>& deoptimize_dependent_code() {
+    return deoptimize_dependent_code_;
+  }
+
   ZoneGrowableArray<const LibraryPrefix*>* deferred_prefixes() const {
     return deferred_prefixes_;
   }
@@ -363,6 +367,7 @@ class FlowGraph : public ZoneAllocated {
   ZoneGrowableArray<BlockEntryInstr*>* loop_headers_;
   ZoneGrowableArray<BitVector*>* loop_invariant_loads_;
   ZoneGrowableArray<const Field*>* guarded_fields_;
+  GrowableArray<const Field*> deoptimize_dependent_code_;
   ZoneGrowableArray<const LibraryPrefix*>* deferred_prefixes_;
   DirectChainedHashMap<ConstantPoolTrait> constant_instr_pool_;
   BitVector* captured_parameters_;