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

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index fcd11a1960884cf656baec91ff52067c5a25f670..8ac996cdf7db5926e464f1e377d985ce13dd7140 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6774,8 +6774,8 @@ class SharedFunctionInfo: public HeapObject {
   inline int end_position() const;
   inline void set_end_position(int end_position);
 
-  // Is this function a function expression in the source code.
-  DECL_BOOLEAN_ACCESSORS(is_expression)
+  // Is this function a named function expression in the source code.
+  DECL_BOOLEAN_ACCESSORS(is_named_expression)
 
   // Is this function a top-level function (scripts, evals).
   DECL_BOOLEAN_ACCESSORS(is_toplevel)
@@ -6843,9 +6843,10 @@ class SharedFunctionInfo: public HeapObject {
   // see a binding for it.
   DECL_BOOLEAN_ACCESSORS(name_should_print_as_anonymous)
 
-  // Indicates that the function is anonymous (the name field can be set
-  // through the API, which does not change this flag).
-  DECL_BOOLEAN_ACCESSORS(is_anonymous)
+  // Indicates that the function is either an anonymous expression
+  // or an arrow function (the name field can be set through the API,
+  // which does not change this flag).
+  DECL_BOOLEAN_ACCESSORS(is_anonymous_expression)
 
   // Is this a function or top-level/eval code.
   DECL_BOOLEAN_ACCESSORS(is_function)
@@ -6880,6 +6881,9 @@ class SharedFunctionInfo: public HeapObject {
   // Indicates that the the shared function info has never been compiled before.
   DECL_BOOLEAN_ACCESSORS(never_compiled)
 
+  // Whether this function was created from a FunctionDeclaration.
+  DECL_BOOLEAN_ACCESSORS(is_declaration)
+
   inline FunctionKind kind();
   inline void set_kind(FunctionKind kind);
 
@@ -7113,10 +7117,10 @@ class SharedFunctionInfo: public HeapObject {
   // Bit positions in start_position_and_type.
   // The source code start position is in the 30 most significant bits of
   // the start_position_and_type field.
-  static const int kIsExpressionBit    = 0;
-  static const int kIsTopLevelBit      = 1;
+  static const int kIsNamedExpressionBit = 0;
+  static const int kIsTopLevelBit = 1;
   static const int kStartPositionShift = 2;
-  static const int kStartPositionMask  = ~((1 << kStartPositionShift) - 1);
+  static const int kStartPositionMask = ~((1 << kStartPositionShift) - 1);
 
   // Bit positions in compiler_hints.
   enum CompilerHints {
@@ -7133,7 +7137,7 @@ class SharedFunctionInfo: public HeapObject {
     kHasDuplicateParameters,
     kForceInline,
     kIsAsmFunction,
-    kIsAnonymous,
+    kIsAnonymousExpression,
     kNameShouldPrintAsAnonymous,
     kIsFunction,
     kDontCrankshaft,
@@ -7150,6 +7154,7 @@ class SharedFunctionInfo: public HeapObject {
     // byte 3
     kDeserialized,
     kNeverCompiled,
+    kIsDeclaration,
     kCompilerHintsCount,  // Pseudo entry
   };
   // Add hints for other modes when they're added.