[turbofan] Don't spread global flag checks all over the compiler code.

test/unittests/compiler/instruction-selector-unittest.h

 // 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.
 
 #ifndef V8_UNITTESTS_COMPILER_INSTRUCTION_SELECTOR_UNITTEST_H_
 #define V8_UNITTESTS_COMPILER_INSTRUCTION_SELECTOR_UNITTEST_H_
 
 #include <deque>
 #include <set>
 
@@ skipping 55 matching lines @@
     Stream Build(CpuFeature feature) {
       return Build(InstructionSelector::Features(feature));
     }
     Stream Build(CpuFeature feature1, CpuFeature feature2) {
       return Build(InstructionSelector::Features(feature1, feature2));
     }
     Stream Build(StreamBuilderMode mode = kTargetInstructions) {
       return Build(InstructionSelector::Features(), mode);
     }
     Stream Build(InstructionSelector::Features features,
-                 StreamBuilderMode mode = kTargetInstructions);
+                 StreamBuilderMode mode = kTargetInstructions,
+                 InstructionSelector::SourcePositionMode source_position_mode =
+                     InstructionSelector::kAllSourcePositions);
 
    private:
     MachineSignature* MakeMachineSignature(Zone* zone,
                                            MachineType return_type) {
       MachineSignature::Builder builder(zone, 1, 0);
       builder.AddReturn(return_type);
       return builder.Build();
     }
 
     MachineSignature* MakeMachineSignature(Zone* zone, MachineType return_type,
@@ skipping 154 matching lines @@
 template <typename T>
 class InstructionSelectorTestWithParam
     : public InstructionSelectorTest,
       public ::testing::WithParamInterface<T> {};
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UNITTESTS_COMPILER_INSTRUCTION_SELECTOR_UNITTEST_H_