Compute local variable liveness before translation to SSA.

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 9e6ee4efe41b9e45abc243c7dc5c4136ccd598a2..feceb41e84c967646934e1baa483a91d95383089 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -3252,7 +3252,7 @@ class LoadOptimizer : public ValueObject {
           for (intptr_t i = 0; i < block->PredecessorCount(); i++) {
             BlockEntryInstr* pred = block->PredecessorAt(i);
             BitVector* pred_out = out_[pred->preorder_number()];
-            temp->Intersect(*pred_out);
+            temp->Intersect(pred_out);
           }
         }
 
@@ -4435,6 +4435,8 @@ void ConstantPropagator::Transform() {
         // Replace the false target entry with the new join entry. We will
         // recompute the dominators after this pass.
         join->LinkTo(next);
+        jump->SetEnvironment(branch->env());
+        branch->SetEnvironment(NULL);
         branch->UnuseAllInputs();
       }
     }