VM: Propagate non-nullness from instance calls.

runtime/vm/flow_graph_type_propagator.h

Index: runtime/vm/flow_graph_type_propagator.h
diff --git a/runtime/vm/flow_graph_type_propagator.h b/runtime/vm/flow_graph_type_propagator.h
index ec933c2ab64fc8831ca671d4156a3c223da48d28..9214e1d61867cafdb9d3dfbb2e0596bdadb57b52 100644
--- a/runtime/vm/flow_graph_type_propagator.h
+++ b/runtime/vm/flow_graph_type_propagator.h
@@ -37,6 +37,10 @@ class FlowGraphTypePropagator : public FlowGraphVisitor {
       PolymorphicInstanceCallInstr* instr);
   virtual void VisitBranch(BranchInstr* instr);
 
+  void CheckNonNullSelector(Instruction* call,
+                            Definition* receiver,
+                            const String& function_name);
+
   // Current reaching type of the definition. Valid only during dominator tree
   // traversal.
   CompileType* TypeOf(Definition* def);