Web Replay: memoize nondeterministic attributes of the Navigator interface

Web Replay: memoize nondeterministic attributes of the Navigator interface
https://bugs.webkit.org/show_bug.cgi?id=131340

Reviewed by Timothy Hatcher.

.:

* ManualTests/inspector/replay-window-navigator-basic.html: Added.

Source/WebCore:

Most attributes of window.navigator do not change very often, but they
could be easily changed by the user or embedder. So, memoize attribute values.

This change does not include navigator.mimeTypes and navigator.plugins,
which will be handled at a different level. <https://webkit.org/b/131341>

Test: ManualTests/inspector/replay-window-navigator-basic.html

* page/Navigator.idl: Add Nondeterministic attribute.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@167157 268f45cc-cd09-0410-ab3c-d52691b4dbfc