Reland of [turbofan] Insert dummy values when changing from None type.

src/compiler/arm64/code-generator-arm64.cc

 // Copyright 2014 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/code-generator.h"
 
 #include "src/arm64/frames-arm64.h"
 #include "src/arm64/macro-assembler-arm64.h"
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
@@ skipping 748 matching lines @@
       break;
     case kArchTableSwitch:
       AssembleArchTableSwitch(instr);
       break;
     case kArchLookupSwitch:
       AssembleArchLookupSwitch(instr);
       break;
     case kArchDebugBreak:
       __ Debug("kArchDebugBreak", 0, BREAK);
       break;
-    case kArchImpossible:
-      __ Abort(kConversionFromImpossibleValue);
-      break;
     case kArchComment: {
       Address comment_string = i.InputExternalReference(0).address();
       __ RecordComment(reinterpret_cast<const char*>(comment_string));
       break;
     }
     case kArchNop:
     case kArchThrowTerminator:
       // don't emit code for nops.
       break;
     case kArchDeoptimize: {
@@ skipping 1303 matching lines @@
       padding_size -= kInstructionSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8