[turbofan]: No tabs in tokens in JSON graph files (ECMA404 compliance).

src/ostreams.cc

Index: src/ostreams.cc
diff --git a/src/ostreams.cc b/src/ostreams.cc
index c3532bdbb1412c9c3461c3980debadfa4cff42f0..a7a67f5d2f06002fc9899b7c391476fd16022932 100644
--- a/src/ostreams.cc
+++ b/src/ostreams.cc
@@ -71,6 +71,7 @@ std::ostream& operator<<(std::ostream& os, const AsReversiblyEscapedUC16& c) {
 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 == '\t') return os << "\\t";
   if (c.value == '\"') return os << "\\\"";
   return PrintUC16(os, c.value, IsOK);
 }