Fix broken debug build: prevent adding the same cid twice.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
diff --git a/runtime/vm/flow_graph_optimizer.cc b/runtime/vm/flow_graph_optimizer.cc
index 1b65299e8944e21689f5aead779e5a26a5f8652a..cc16479ee5e0473b76f6089f88ce6121ad8b1a88 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -164,7 +164,7 @@ static bool IsNumberCid(intptr_t cid) {
 // Attempt to build ICData for call using propagated class-ids.
 bool FlowGraphOptimizer::TryCreateICData(InstanceCallInstr* call) {
   ASSERT(call->HasICData());
-  if (call->ic_data()->NumberOfUsedChecks() > 0) {
+  if (call->ic_data()->NumberOfChecks() > 0) {
     // This occurs when an instance call has too many checks, will be converted
     // to megamorphic call.
     return false;