Align HTMLAppletElement IDL with spec

LayoutTests/fast/dom/script-tests/unsigned-long-attribute-reflection.js

+// http://whatwg.org/html#reflecting-content-attributes-in-idl-attributes
+// http://whatwg.org/html#rules-for-parsing-non-negative-integers
+function testUnsignedLong(interface, createElement, attribute)
+{
+    test(function()
+    {
+        var element = createElement();
+
+        assert_equals(element[attribute], 0);
+
+        function t(input, output)
+        {
+            element.setAttribute(attribute, input);
+            assert_equals(element[attribute], output);
+        }
+
+        t("", 0);
+        t("0", 0);
+        t("1", 1);
+        t("2147483647", 2147483647);
+        t("2147483648", 0);
+        t("-1", 0);
+        t("+42", 42);
+        t(" 42", 42);
+        t("42!", 42);
+    }, "get " + interface + "." + attribute);
+
+    test(function()
+    {
+        var element = createElement();
+
+        assert_false(element.hasAttribute(attribute));
+
+        function t(input, output)
+        {
+            element[attribute] = input;
+            assert_equals(element.getAttribute(attribute), output);
+        }
+
+        t(0, "0");
+        t(2147483647, "2147483647");
+        // per spec:
+        //t(2147483648, "0");
+        //t(-1, "0");
+        // per implementation <http://crbug.com/316122>:
+        t(2147483648, "2147483648");
+        t(-1, "4294967295");
+    }, "set " + interface + "." + attribute);
+}