[turbofan] Drop V8_TURBOFAN_BACKEND and V8_TURBOFAN_TARGET defines.

src/compiler/pipeline.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/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/adapters.h"
@@ skipping 1058 matching lines @@
 
   // Remove dead->live edges from the graph.
   Run<EarlyGraphTrimmingPhase>();
   RunPrintAndVerify("Early trimmed", true);
 
   if (FLAG_print_turbo_replay) {
     // Print a replay of the initial graph.
     GraphReplayPrinter::PrintReplay(data.graph());
   }
 
-  // Bailout here in case target architecture is not supported.
-  if (!SupportedTarget()) return Handle<Code>::null();
-
   base::SmartPointer<Typer> typer;
   if (info()->is_typing_enabled()) {
     // Type the graph.
     typer.Reset(new Typer(isolate(), data.graph(), info()->function_type()));
     Run<TyperPhase>(typer.get());
     RunPrintAndVerify("Typed");
   }
 
   BeginPhaseKind("lowering");
 
@@ skipping 104 matching lines @@
   pipeline.AllocateRegisters(config, run_verifier);
   return !data.compilation_failed();
 }
 
 
 Handle<Code> Pipeline::ScheduleAndGenerateCode(
     CallDescriptor* call_descriptor) {
   PipelineData* data = this->data_;
 
   DCHECK_NOT_NULL(data->graph());
-  CHECK(SupportedBackend());
 
   if (data->schedule() == nullptr) Run<ComputeSchedulePhase>();
   TraceSchedule(data->info(), data->schedule());
 
   BasicBlockProfiler::Data* profiler_data = NULL;
   if (FLAG_turbo_profiling) {
     profiler_data = BasicBlockInstrumentor::Instrument(info(), data->graph(),
                                                        data->schedule());
   }
 
@@ skipping 156 matching lines @@
     tcf << AsC1VRegisterAllocationData("CodeGen",
                                        data->register_allocation_data());
   }
 
   data->DeleteRegisterAllocationZone();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8