New class for Date objects: caches individual date components.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 7308fb2bc3ca4792c319b5c4648d3c55857e424f..78e8458cfc21c634d0a7a5c9e546d9c286ea1a17 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -595,6 +595,7 @@ TYPE_CHECKER(Oddball, ODDBALL_TYPE)
 TYPE_CHECKER(JSGlobalPropertyCell, JS_GLOBAL_PROPERTY_CELL_TYPE)
 TYPE_CHECKER(SharedFunctionInfo, SHARED_FUNCTION_INFO_TYPE)
 TYPE_CHECKER(JSValue, JS_VALUE_TYPE)
+TYPE_CHECKER(JSDate, JS_DATE_TYPE)
 TYPE_CHECKER(JSMessageObject, JS_MESSAGE_OBJECT_TYPE)
 
 
@@ -1390,6 +1391,8 @@ int JSObject::GetHeaderSize() {
       return JSFunction::kSize;
     case JS_VALUE_TYPE:
       return JSValue::kSize;
+    case JS_DATE_TYPE:
+      return JSDate::kSize;
     case JS_ARRAY_TYPE:
       return JSArray::kSize;
     case JS_WEAK_MAP_TYPE:
@@ -4022,6 +4025,23 @@ JSValue* JSValue::cast(Object* obj) {
 }
 
 
+ACCESSORS(JSDate, value, Object, kValueOffset)
+ACCESSORS(JSDate, year, Object, kYearOffset)
+ACCESSORS(JSDate, month, Object, kMonthOffset)
+ACCESSORS(JSDate, day, Object, kDayOffset)
+ACCESSORS(JSDate, hour, Object, kHourOffset)
+ACCESSORS(JSDate, min, Object, kMinOffset)
+ACCESSORS(JSDate, sec, Object, kSecOffset)
+ACCESSORS(JSDate, ms, Object, kMsOffset)
+
+
+JSDate* JSDate::cast(Object* obj) {
+  ASSERT(obj->IsJSDate());
+  ASSERT(HeapObject::cast(obj)->Size() == JSDate::kSize);
+  return reinterpret_cast<JSDate*>(obj);
+}
+
+
 ACCESSORS(JSMessageObject, type, String, kTypeOffset)
 ACCESSORS(JSMessageObject, arguments, JSArray, kArgumentsOffset)
 ACCESSORS(JSMessageObject, script, Object, kScriptOffset)