Add a script that can generate simple test cases for user-exposed JS builtins

tools/detect-builtins.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+(function(global) {
+
+  var GetProperties = function(this_name, object) {
+    var result = {};
+    try {
+      var names = Object.getOwnPropertyNames(object);
+    } catch(e) {
+      return;
+    }
+    for (var i = 0; i < names.length; ++i) {
+      var name = names[i];
+      if (typeof object === "function") {
+        if (name === "length" ||
+            name === "name" ||
+            name === "arguments" ||
+            name === "caller" ||
+            name === "prototype") {
+          continue;
+        }
+      }
+      // Avoid endless recursion.
+      if (this_name === "prototype" && name === "constructor") continue;
+      // Could get this from the parent, but having it locally is easier.
+      var property = { "name": name };
+      try {
+        var value = object[name];
+      } catch(e) {
+        property.type = "getter";
+        result[name] = property;
+        continue;
+      }
+      var type = typeof value;
+      property.type = type;
+      if (type === "function") {
+        property.length = value.length;
+        property.prototype = GetProperties("prototype", value.prototype);
+      }
+      property.properties = GetProperties(name, value);
+      result[name] = property;
+    }
+    return result;
+  };
+
+  var g = GetProperties("", global, "");
+  print(JSON.stringify(g, undefined, 2));
+
+})(this);  // Must wrap in anonymous closure or it'll detect itself as builtin.