[turbofan] Proper dead code elimination as regular reducer.

src/compiler/ast-graph-builder.h

Index: src/compiler/ast-graph-builder.h
diff --git a/src/compiler/ast-graph-builder.h b/src/compiler/ast-graph-builder.h
index 69b356063b15b3204c04bd91c853a0acbb7af4b0..14ebc22f03c9063b4b9a43f4fff0b4b3cd9917e1 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -485,11 +485,11 @@ class AstGraphBuilder::Environment : public ZoneObject {
 
   // Mark this environment as being unreachable.
   void MarkAsUnreachable() {
-    UpdateControlDependency(builder()->jsgraph()->DeadControl());
+    UpdateControlDependency(builder()->jsgraph()->Dead());
     liveness_block_ = nullptr;
   }
   bool IsMarkedAsUnreachable() {
-    return GetControlDependency()->opcode() == IrOpcode::kDeadControl;
+    return GetControlDependency()->opcode() == IrOpcode::kDead;
   }
 
   // Merge another environment into this one.