[turbofan] Improve JSON output

src/compiler/graph-visualizer.h

 // Copyright 2013 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_COMPILER_GRAPH_VISUALIZER_H_
 #define V8_COMPILER_GRAPH_VISUALIZER_H_
 
 #include <iosfwd>
 
 namespace v8 {
@@ skipping 12 matching lines @@
 
 struct AsDOT {
   explicit AsDOT(const Graph& g) : graph(g) {}
   const Graph& graph;
 };
 
 std::ostream& operator<<(std::ostream& os, const AsDOT& ad);
 
 
 struct AsJSON {
-  explicit AsJSON(const Graph& g) : graph(g) {}
+  AsJSON(const Graph& g, SourcePositionTable* p) : graph(g), positions(p) {}
   const Graph& graph;
+  const SourcePositionTable* positions;
 };
 
 std::ostream& operator<<(std::ostream& os, const AsJSON& ad);
 
 struct AsRPO {
   explicit AsRPO(const Graph& g) : graph(g) {}
   const Graph& graph;
 };
 
 std::ostream& operator<<(std::ostream& os, const AsRPO& ad);
@@ skipping 30 matching lines @@
 std::ostream& operator<<(std::ostream& os, const AsDOT& ad);
 std::ostream& operator<<(std::ostream& os, const AsC1VCompilation& ac);
 std::ostream& operator<<(std::ostream& os, const AsC1V& ac);
 std::ostream& operator<<(std::ostream& os, const AsC1VAllocator& ac);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_GRAPH_VISUALIZER_H_