fix pl, context.js .. Fibers.current._meteor_dynamics = []

[yosiah]

https://stackoverflow.com/questions/45620780/meteor-error-on-fast-rendering-path-typeerror-dynamics-slice-is-not-a-function

W20181103-18:33:03.354(9)? (STDERR) error on fast-rendering path: / ; error: TypeError: dynamics.slice is not a function
W20181103-18:33:03.355(9)? (STDERR) at Object.Meteor.bindEnvironment (packages\meteor.js:1333:41)
W20181103-18:33:03.359(9)? (STDERR) at PublishContext.onStop (packages/ddp-server/livedata_server.js:1226:23)
W20181103-18:33:03.360(9)? (STDERR) at Context.processPublication (packages\meteorhacks_fast-render.js:497:18)
W20181103-18:33:03.361(9)? (STDERR) at packages\meteorhacks_fast-render.js:313:15
W20181103-18:33:03.362(9)? (STDERR) at Array.forEach ()
W20181103-18:33:03.363(9)? (STDERR) at Context. (packages\meteorhacks_fast-render.js:310:18)
W20181103-18:33:03.365(9)? (STDERR) at packages\meteorhacks_fast-render.js:285:18
W20181103-18:33:03.366(9)? (STDERR) at Array.forEach ()
W20181103-18:33:03.367(9)? (STDERR) at packages\meteorhacks_fast-render.js:284:31