Bug 965898 - Drop support for XPCWN XOWs. r=gabor

XOWs only allow access to Window and Location, both of which are on WebIDL now.
Bug 965898 - Implement an Xray subclass that we can use to implement HTML5 cross-origin semantics. r=gabor
Bug 965898 - All properties on cross-origin DOM objects should be |own|. r=gabor
Bug 965898 - All properties from cross-origin objects are "configurable", non-enumerable, and non-writable. r=gabor
Bug 965898 - Cross-origin objects should have null prototypes. r=gabor
Bug 965898 - Implement proper behavior for [[Enumerate]] And [[OwnPropertyKeys]]. r=gabor
Bug 965898 - Throw for [[Delete]] and [[DefineOwnProperty]]. r=gabor
Bug 965898 - Don't use a FilteringWrapper to get an unfiltered view in ChromeObjectWrapper. r=gabor

This is necessary because subsequent patches cause us to assert when invoking
getPropertyDescriptor on a FilteringWrapper for which |Policy| denies both GET
and SET.

This stuff is really a mess. I'm looking forward to it going away.
Bug 965898 - Don't reuse the JSPropertyDescriptor in BaseProxyHandler::keys. r=gabor

This causes garbage from a previous lookup to propagate into subsequent lookups,
and creates confusing situations (like having both a value and a getter).
Bug 965898 - Generalize FilterSetter to work on all the relevant fields of JSPropertyDescriptor. r=gabor
Bug 965898 - Switch policies for get{,Own}PropertyDescriptor. r=gabor
Bug 965898 - Squelch exceptions during the shadowing detection in isCrossOriginAccessPermitted. r=gabor
Bug 965898 - Allow both gettable and settable attributes in Filter(). r=gabor
Bug 965898 - Add subdomains for mochi.test. r=ted

This allows us to test document.domain without hoisting the whole test into
an example.com iframe.
Bug 965898 - Import web-platform-test into the tree. r=Ms2ger
Bug 965898 - Handleify more stuff. r=me