[turbofan] Drop V8_TURBOFAN_BACKEND and V8_TURBOFAN_TARGET defines.

test/cctest/compiler/test-run-stubs.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/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/pipeline.h"
 #include "src/parser.h"
 #include "test/cctest/compiler/function-tester.h"
 
-#if V8_TURBOFAN_TARGET
-
 using namespace v8::internal;
 using namespace v8::internal::compiler;
 
 
 TEST(RunOptimizedMathFloorStub) {
   HandleAndZoneScope scope;
   Isolate* isolate = scope.main_isolate();
 
   // Create code and an accompanying descriptor.
   MathFloorStub stub(isolate, TurboFanIC::CALL_FROM_OPTIMIZED_CODE);
@@ skipping 110 matching lines @@
   graph.SetStart(start);
   graph.SetEnd(end);
   FunctionTester ft(&graph);
 
   // Actuall call through to the stub, verifying its result.
   Handle<String> leftArg = ft.Val("links");
   Handle<String> rightArg = ft.Val("rechts");
   Handle<Object> result = ft.Call(leftArg, rightArg).ToHandleChecked();
   CHECK(String::Equals(ft.Val("linksrechts"), Handle<String>::cast(result)));
 }
-
-#endif  // V8_TURBOFAN_TARGET