Fix build bustage caused by Bug 738121. r=me

--HG--
extra : rebase_source : 9943ace287e944ed84565a3d71271d411815c659

dom/system/nsDeviceMotion.cpp

@@ -126,7 +126,6 @@ nsDeviceMotion::nsDeviceMotion()
   mEnabled(true)
 {
   mLastDOMMotionEventTime = TimeStamp::Now();
-  mLastAccuracy = SENSOR_ACCURACY_UNKNOWN;
 
   nsCOMPtr<nsIPrefBranch> prefSrv = do_GetService(NS_PREFSERVICE_CONTRACTID);
   if (prefSrv) {