[turbofan] Handle impossible types (Type::None()) in the backend.

src/compiler/instruction-scheduler.cc

 // 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.
 
 #include "src/compiler/instruction-scheduler.h"
 
 #include "src/base/adapters.h"
 #include "src/base/utils/random-number-generator.h"
 
 namespace v8 {
@@ skipping 205 matching lines @@
 
 
 int InstructionScheduler::GetInstructionFlags(const Instruction* instr) const {
   switch (instr->arch_opcode()) {
     case kArchNop:
     case kArchFramePointer:
     case kArchParentFramePointer:
     case kArchTruncateDoubleToI:
     case kArchStackSlot:
     case kArchDebugBreak:
+    case kArchImpossible:
     case kArchComment:
     case kIeee754Float64Acos:
     case kIeee754Float64Acosh:
     case kIeee754Float64Asin:
     case kIeee754Float64Asinh:
     case kIeee754Float64Atan:
     case kIeee754Float64Atanh:
     case kIeee754Float64Atan2:
     case kIeee754Float64Cbrt:
     case kIeee754Float64Cos:
@@ skipping 124 matching lines @@
       }
     }
 
     node->set_total_latency(max_latency + node->latency());
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8