[turbofan] Properly handle deoptimizations in the instruction scheduler.

src/compiler/instruction-scheduler.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_INSTRUCTION_SCHEDULER_H_
 #define V8_COMPILER_INSTRUCTION_SCHEDULER_H_
 
 #include "src/compiler/instruction.h"
 #include "src/zone-containers.h"
 
@@ skipping 191 matching lines @@
   // which will be added as predecessors of the next instruction with side
   // effects.
   ZoneVector<ScheduleGraphNode*> pending_loads_;
 
   // Live-in register markers are nop instructions which are emitted at the
   // beginning of a basic block so that the register allocator will find a
   // defining instruction for live-in values. They must not be moved.
   // 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
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SCHEDULER_H_