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

src/compiler/simplified-lowering.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/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 93 matching lines @@
     }
 
     // Run lowering and change insertion phase.
     TRACE("--{Simplified lowering phase}--\n");
     phase_ = LOWER;
     // Process nodes from the collected {nodes_} vector.
     for (NodeVector::iterator i = nodes_.begin(); i != nodes_.end(); ++i) {
       Node* node = *i;
       TRACE(" visit #%d: %s\n", node->id(), node->op()->mnemonic());
       // Reuse {VisitNode()} so the representation rules are in one place.
-      if (FLAG_turbo_source_positions) {
-        SourcePositionTable::Scope scope(
-            source_positions_, source_positions_->GetSourcePosition(node));
-        VisitNode(node, GetUseInfo(node), lowering);
-      } else {
-        VisitNode(node, GetUseInfo(node), lowering);
-      }
+      SourcePositionTable::Scope scope(
+          source_positions_, source_positions_->GetSourcePosition(node));
+      VisitNode(node, GetUseInfo(node), lowering);
     }
 
     // Perform the final replacements.
     for (NodeVector::iterator i = replacements_.begin();
          i != replacements_.end(); ++i) {
       Node* node = *i;
       Node* replacement = *(++i);
       node->ReplaceUses(replacement);
       // We also need to replace the node in the rest of the vector.
       for (NodeVector::iterator j = i + 1; j != replacements_.end(); ++j) {
@@ skipping 1459 matching lines @@
 
 void SimplifiedLowering::DoStringLessThanOrEqual(Node* node) {
   node->set_op(machine()->IntLessThanOrEqual());
   node->ReplaceInput(0, StringComparison(node, true));
   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8