[turbofan] Properly handle deoptimizations in the instruction scheduler.

src/compiler/instruction-scheduler.h

Index: src/compiler/instruction-scheduler.h
diff --git a/src/compiler/instruction-scheduler.h b/src/compiler/instruction-scheduler.h
index 104c0b97de8bd401d2a39c42d7bbfac81f38bec9..464f8b79527450edf6efb506d996ae1b7ec9dc87 100644
--- a/src/compiler/instruction-scheduler.h
+++ b/src/compiler/instruction-scheduler.h
@@ -209,6 +209,9 @@ class InstructionScheduler final : public ZoneObject {
   // All these nops are chained together and added as a predecessor of every
   // other instructions in the basic block.
   ScheduleGraphNode* last_live_in_reg_marker_;
+
+  // Last deoptimization instruction encountered while building the graph.
+  ScheduleGraphNode* last_deopt_;
 };
 
 }  // namespace compiler