Revert of [turbofan] Implemented the TruncateFloat32ToInt64 TurboFan operator.

src/compiler/mips64/code-generator-mips64.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/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
 #include "src/mips/macro-assembler-mips.h"
@@ skipping 973 matching lines @@
       __ Cvt_s_ul(i.OutputDoubleRegister(), i.InputRegister(0));
       break;
     }
     case kMips64TruncWD: {
       FPURegister scratch = kScratchDoubleReg;
       // Other arches use round to zero here, so we follow.
       __ trunc_w_d(scratch, i.InputDoubleRegister(0));
       __ mfc1(i.OutputRegister(), scratch);
       break;
     }
-    case kMips64TruncLS: {
-      FPURegister scratch = kScratchDoubleReg;
-      // Other arches use round to zero here, so we follow.
-      __ trunc_l_s(scratch, i.InputDoubleRegister(0));
-      __ dmfc1(i.OutputRegister(), scratch);
-      break;
-    }
     case kMips64TruncLD: {
       FPURegister scratch = kScratchDoubleReg;
       // Other arches use round to zero here, so we follow.
       __ trunc_l_d(scratch, i.InputDoubleRegister(0));
       __ dmfc1(i.OutputRegister(), scratch);
       break;
     }
     case kMips64TruncUwD: {
       FPURegister scratch = kScratchDoubleReg;
       // TODO(plind): Fix wrong param order of Trunc_uw_d() macro-asm function.
@@ skipping 724 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8