Partial progress on workbox externs.

workbox-externs.js

var workbox = {
    clientsClaim: function(){},
    loadModule: function(string){},
    setConfig: function(object){},
    skipWaiting: function(){},
    core: {
        cacheNames: {},
        LOG_LEVELS: {},
        setCacheNameDetails: function(){},
        setLogLevel: function(){},
    },
    precaching: {
        PrecacheController: {},
        addPlugins: function(){},
        addRoute: function (object){},
        precache: function(){},
        precacheAndRoute: function(){},
        supressWarnings: function(){},
        CleanupResult: {},
        InstallResult: {},
        PrecacheEntry: {},
    },
    strategies: {
        cacheFirst: function(){},
        cacheOnly: function(){},
        networkFirst: function(){},
        networkOnly: function(){},
        staleWhileRevalidate: function(){},
    },
    routing: {},
    expiration: {},
    backgroundSync: {},
    googleAnalytics: {},
    cacheableResponse: {},
    broadcastUpdate: {},
    rangeRequests: {}
}