Revert r35682, one test is failing: standalone/io/process_sync_test. Code may actually be changing …

runtime/vm/flow_graph_allocator.cc

Index: runtime/vm/flow_graph_allocator.cc
===================================================================
--- runtime/vm/flow_graph_allocator.cc	(revision 35682)
+++ runtime/vm/flow_graph_allocator.cc	(working copy)
@@ -231,6 +231,12 @@
     kill_[graph_entry_->postorder_number()]->Add(vreg);
     live_in_[graph_entry_->postorder_number()]->Remove(vreg);
   }
+
+  // Update initial live_in sets to match live_out sets. Has to be
+  // done in a separate path because of backwards branches.
+  for (intptr_t i = 0; i < block_count; i++) {
+    UpdateLiveIn(*postorder_[i]);
+  }
 }