New class for Date objects: caches individual date components.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index cedb0efd00127bf54461832b2b706de4db675d0c..27cd0e0b5e5274a42fb23ae5666a40aecb28f5dd 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -947,7 +947,7 @@ void Genesis::InitializeGlobal(Handle<GlobalObject> inner_global,
   {  // --- D a t e ---
     // Builtin functions for Date.prototype.
     Handle<JSFunction> date_fun =
-        InstallFunction(global, "Date", JS_VALUE_TYPE, JSValue::kSize,
+        InstallFunction(global, "Date", JS_DATE_TYPE, JSDate::kSize,
                         isolate->initial_object_prototype(),
                         Builtins::kIllegal, true);