Change comparison-to-branch fusion to actually remove comparison from the graph.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
diff --git a/runtime/vm/flow_graph_builder.cc b/runtime/vm/flow_graph_builder.cc
index eb1ccda6c1e9a3209868f21879776b0112d518ad..dc3af0d1f86e8c1cb58c2c058df9c738303c01dc 100644
--- a/runtime/vm/flow_graph_builder.cc
+++ b/runtime/vm/flow_graph_builder.cc
@@ -2259,7 +2259,8 @@ void FlowGraphBuilder::BuildGraph(bool for_optimized, bool use_ssa) {
   for (intptr_t i = 0; i < block_count; ++i) {
     postorder_block_entries_[i]->set_block_id(block_count - i - 1);
   }
-  if (for_optimized && use_ssa) {
+
+  if (for_optimized) {
     // Link instructions backwards for optimized compilation.
     for (intptr_t i = 0; i < block_count; ++i) {
       BlockEntryInstr* entry = postorder_block_entries_[i];
@@ -2270,6 +2271,9 @@ void FlowGraphBuilder::BuildGraph(bool for_optimized, bool use_ssa) {
         previous = current;
       }
     }
+  }
+
+  if (for_optimized && use_ssa) {
     GrowableArray<BitVector*> dominance_frontier;
     ComputeDominators(&preorder_block_entries_, &parent, &dominance_frontier);
     InsertPhis(preorder_block_entries_,