VM: [Cleanup] Delete legacy code associated with BranchInstr.

runtime/vm/flow_graph_type_propagator.cc

Index: runtime/vm/flow_graph_type_propagator.cc
diff --git a/runtime/vm/flow_graph_type_propagator.cc b/runtime/vm/flow_graph_type_propagator.cc
index 928c533f3b31e86b567cb95da10377cda995c6f9..782ea05234f7166d6e33c85c06cf6d12c7456799 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -98,18 +98,6 @@ void FlowGraphTypePropagator::Propagate() {
         if (use_defn != NULL) {
           AddToWorklist(use_defn);
         }
-
-        // If the value flow into a branch recompute type constrained by the
-        // branch (if any). This ensures that correct non-nullable type will
-        // flow downwards from the branch on the comparison with the null
-        // constant.
-        BranchInstr* branch = instr->AsBranch();
-        if (branch != NULL) {
-          ConstrainedCompileType* constrained_type = branch->constrained_type();
-          if (constrained_type != NULL) {
-            constrained_type->Update();
-          }
-        }
       }
     }
   }
@@ -199,19 +187,6 @@ void FlowGraphTypePropagator::SetCid(Definition* def, intptr_t cid) {
 }
 
 
-ConstrainedCompileType* FlowGraphTypePropagator::MarkNonNullable(
-    Definition* def) {
-  CompileType* current = TypeOf(def);
-  if (current->is_nullable() && (current->ToCid() != kNullCid)) {
-    ConstrainedCompileType* constrained_type =
-        new NotNullConstrainedCompileType(current);
-    SetTypeOf(def, constrained_type->ToCompileType());
-    return constrained_type;
-  }
-  return NULL;
-}
-
-
 void FlowGraphTypePropagator::VisitValue(Value* value) {
   CompileType* type = TypeOf(value->definition());
   value->SetReachingType(type);