[turbofan] Improve JSON output

src/ostreams.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/ostreams.h"
 
 #if V8_OS_WIN
 #define snprintf sprintf_s
 #endif
 
@@ skipping 48 matching lines @@
 }
 
 }  // namespace
 
 
 std::ostream& operator<<(std::ostream& os, const AsReversiblyEscapedUC16& c) {
   return PrintUC16(os, c.value, IsOK);
 }
 
 
+std::ostream& operator<<(std::ostream& os, const AsEscapedUC16ForJSON& c) {
+  if (c.value == '\n') return os << "\\n";
+  if (c.value == '\r') return os << "\\r";
+  if (c.value == '\"') return os << "\\\"";
+  if (c.value == '\'') return os << "\\\'";
+  return PrintUC16(os, c.value, IsOK);
+}
+
+
 std::ostream& operator<<(std::ostream& os, const AsUC16& c) {
   return PrintUC16(os, c.value, IsPrint);
 }
 
 }  // namespace internal
 }  // namespace v8