Convert function.prototype to API-style accessor.

src/accessors.h

Index: src/accessors.h
diff --git a/src/accessors.h b/src/accessors.h
index 196bce56998999606fb4c172036e583ea620949e..48d96c2d723b3eca976d1d467e8e9345da414ff6 100644
--- a/src/accessors.h
+++ b/src/accessors.h
@@ -37,7 +37,6 @@ namespace internal {
 // The list of accessor descriptors. This is a second-order macro
 // taking a macro to be applied to all accessor descriptor names.
 #define ACCESSOR_DESCRIPTOR_LIST(V) \
-  V(FunctionPrototype)              \
   V(FunctionLength)                 \
   V(FunctionName)                   \
   V(FunctionArguments)              \
@@ -45,6 +44,7 @@ namespace internal {
   V(ArrayLength)
 
 #define ACCESSOR_INFO_LIST(V)       \
+  V(FunctionPrototype)              \
   V(ScriptColumnOffset)             \
   V(ScriptCompilationType)          \
   V(ScriptContextData)              \
@@ -115,13 +115,6 @@ class Accessors : public AllStatic {
 
  private:
   // Accessor functions only used through the descriptor.
-  static MaybeObject* FunctionSetPrototype(Isolate* isolate,
-                                           JSObject* object,
-                                           Object*,
-                                           void*);
-  static MaybeObject* FunctionGetPrototype(Isolate* isolate,
-                                           Object* object,
-                                           void*);
   static MaybeObject* FunctionGetLength(Isolate* isolate,
                                         Object* object,
                                         void*);