Don't reflect ES2015 Function name inference in Function.prototype.toString

src/objects-printer.cc

 // Copyright 2012 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/objects.h"
 
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/objects-inl.h"
@@ skipping 868 matching lines @@
     String* source = String::cast(Script::cast(script())->source());
     int start = start_position();
     int length = end_position() - start;
     base::SmartArrayPointer<char> source_string = source->ToCString(
         DISALLOW_NULLS, FAST_STRING_TRAVERSAL, start, length, NULL);
     os << source_string.get();
   }
   // Script files are often large, hard to read.
   // os << "\n - script =";
   // script()->Print(os);
+  if (is_named_expression()) {
+    os << "\n - named expression";
+  } else if (is_anonymous_expression()) {
+    os << "\n - anonymous expression";
+  } else if (is_declaration()) {
+    os << "\n - declaration";
+  }
   os << "\n - function token position = " << function_token_position();
   os << "\n - start position = " << start_position();
   os << "\n - end position = " << end_position();
-  os << "\n - is expression = " << is_expression();
   os << "\n - debug info = " << Brief(debug_info());
   os << "\n - length = " << length();
   os << "\n - optimized_code_map = " << Brief(optimized_code_map());
   os << "\n - feedback_vector = ";
   feedback_vector()->TypeFeedbackVectorPrint(os);
   if (HasBytecodeArray()) {
     os << "\n - bytecode_array = " << bytecode_array();
   }
   os << "\n";
 }
@@ skipping 413 matching lines @@
 void JSObject::PrintTransitions(std::ostream& os) {  // NOLINT
   Object* transitions = map()->raw_transitions();
   int num_transitions = TransitionArray::NumberOfTransitions(transitions);
   if (num_transitions == 0) return;
   os << "\n - transitions";
   TransitionArray::PrintTransitions(os, transitions, false);
 }
 #endif  // defined(DEBUG) || defined(OBJECT_PRINT)
 }  // namespace internal
 }  // namespace v8