Use an enum for indicating the component of an AccessorPair instead of a boolean flag.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 482b7944644361cd50f0728cc064b5a6dcd0e5fa..2b8888b9ef324fb84d143ab9eef2e6cde59c0cdb 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1360,6 +1360,13 @@ enum SetPropertyMode {
 };
 
 
+// Indicator for one component of an AccessorPair.
+enum AccessorComponent {
+  ACCESSOR_GETTER,
+  ACCESSOR_SETTER
+};
+
+
 // JSReceiver includes types on which properties can be defined, i.e.,
 // JSObject and JSProxy.
 class JSReceiver: public HeapObject {
@@ -1612,10 +1619,10 @@ class JSObject: public JSReceiver {
       bool continue_search);
 
   MUST_USE_RESULT MaybeObject* DefineAccessor(String* name,
-                                              bool is_getter,
+                                              AccessorComponent component,
                                               Object* fun,
                                               PropertyAttributes attributes);
-  Object* LookupAccessor(String* name, bool is_getter);
+  Object* LookupAccessor(String* name, AccessorComponent component);
 
   MUST_USE_RESULT MaybeObject* DefineAccessor(AccessorInfo* info);
 
@@ -2166,12 +2173,12 @@ class JSObject: public JSReceiver {
       PropertyAttributes attributes);
   MUST_USE_RESULT MaybeObject* DefineElementAccessor(
       uint32_t index,
-      bool is_getter,
+      AccessorComponent component,
       Object* fun,
       PropertyAttributes attributes);
   MUST_USE_RESULT MaybeObject* DefinePropertyAccessor(
       String* name,
-      bool is_getter,
+      AccessorComponent component,
       Object* fun,
       PropertyAttributes attributes);
   void LookupInDescriptor(String* name, LookupResult* result);
@@ -7927,9 +7934,14 @@ class AccessorPair: public Struct {
 
   MUST_USE_RESULT MaybeObject* CopyWithoutTransitions();
 
-  // TODO(svenpanne) Evil temporary helper, will vanish soon...
-  void set(bool modify_getter, Object* value) {
-    if (modify_getter) {
+  Object* get(AccessorComponent component) {
+    ASSERT(component == ACCESSOR_GETTER || component == ACCESSOR_SETTER);
+    return (component == ACCESSOR_GETTER) ? getter() : setter();
+  }
+
+  void set(AccessorComponent component, Object* value) {
+    ASSERT(component == ACCESSOR_GETTER || component == ACCESSOR_SETTER);
+    if (component == ACCESSOR_GETTER) {
       set_getter(value);
     } else {
       set_setter(value);