one-liners for the remaining top-50 dart:core classes

sdk/lib/core/object.dart

Index: sdk/lib/core/object.dart
diff --git a/sdk/lib/core/object.dart b/sdk/lib/core/object.dart
index 737f916a3bff7844826c902285b710864e977d7d..975a8a79b4bfd34c770f99c633d6ccb75e4fb1a0 100644
--- a/sdk/lib/core/object.dart
+++ b/sdk/lib/core/object.dart
@@ -5,7 +5,18 @@
 part of dart.core;
 
 /**
- * Everything in Dart is an [Object].
+ * The base class for all Dart objects.
+ *
+ * Because Object is the root of the Dart class hierarchy,
+ * every other Dart class is a subclass of Object.
+ *
+ * When you define a class, you should override [toString]
+ * to return a string describing an instance of that class.
+ * You might also need to define [hashCode] and [==], as described in the
+ * [Implementing map keys]
+ * (http://www.dartlang.org/docs/dart-up-and-running/contents/ch03.html#ch03-implementing-map-keys)
+ * section of the [library tour]
+ * (http://www.dartlang.org/docs/dart-up-and-running/contents/ch03.html).
  */
 class Object {
   /**