bug 856700 - don't check the result of infalible nsTArray::SwapElements() in dom/ r=khuey
bug 856696 - make nsTArray::SwapElements() return void r=jlebar
Bug 857393 - XHR in Web Workers fails to throw XMLHttpRequest::Send failures to callers (ex: NS_ERROR_FILE_NOT_FOUND), exception may be reported erroneously elsewhere. r=bent

try build was:
https://tbpl.mozilla.org/?tree=Try&rev=1757a26ab7b4