Await an async cacheWillUpdate in PrecacheController.install()

[jeffposnick]

R: @philipwalton

Fixes #2285

When we made all of the standard plugins async, we forgot add in an await inside of the PrecacheController.install() method.

[workbox-pr-bot]

PR-Bot Size Plugin

Changed File Sizes

File	Before	After	Change	GZipped
packages/workbox-precaching/build/workbox-precaching.prod.js	5.62 KB	5.63 KB	+0%	2.14 KB

New Files

No new files have been added.

All File Sizes

View Table

File	Before	After	Change	GZipped
packages/workbox-background-sync/build/workbox-background-sync.prod.js	3.87 KB	3.87 KB	0%	1.60 KB
packages/workbox-broadcast-update/build/workbox-broadcast-update.prod.js	1.33 KB	1.33 KB	0%	736 B
packages/workbox-build/build/_types.js	41 B	41 B	0%	61 B
packages/workbox-build/build/generate-sw.js	2.75 KB	2.75 KB	0%	1.23 KB
packages/workbox-build/build/get-manifest.js	1.60 KB	1.60 KB	0%	779 B
packages/workbox-build/build/index.js	613 B	613 B	0%	344 B
packages/workbox-build/build/inject-manifest.js	4.93 KB	4.93 KB	0%	1.90 KB
packages/workbox-cacheable-response/build/workbox-cacheable-response.prod.js	608 B	608 B	0%	354 B
packages/workbox-cli/build/app.js	4.16 KB	4.16 KB	0%	1.64 KB
packages/workbox-cli/build/bin.js	940 B	940 B	0%	502 B
packages/workbox-core/build/workbox-core.prod.js	6.89 KB	6.89 KB	0%	2.85 KB
packages/workbox-expiration/build/workbox-expiration.prod.js	3.01 KB	3.01 KB	0%	1.30 KB
packages/workbox-google-analytics/build/workbox-offline-ga.prod.js	1.97 KB	1.97 KB	0%	914 B
packages/workbox-navigation-preload/build/workbox-navigation-preload.prod.js	657 B	657 B	0%	320 B
packages/workbox-precaching/build/workbox-precaching.prod.js	5.62 KB	5.63 KB	+0%	2.14 KB
packages/workbox-range-requests/build/workbox-range-requests.prod.js	1.63 KB	1.63 KB	0%	807 B
packages/workbox-routing/build/workbox-routing.prod.js	3.10 KB	3.10 KB	0%	1.35 KB
packages/workbox-strategies/build/workbox-strategies.prod.js	4.10 KB	4.10 KB	0%	1.13 KB
packages/workbox-streams/build/workbox-streams.prod.js	1.44 KB	1.44 KB	0%	696 B
packages/workbox-sw/build/workbox-sw.js	1.34 KB	1.34 KB	0%	745 B
packages/workbox-webpack-plugin/build/generate-sw.js	4.72 KB	4.72 KB	0%	1.76 KB
packages/workbox-webpack-plugin/build/index.js	349 B	349 B	0%	255 B
packages/workbox-webpack-plugin/build/inject-manifest.js	6.75 KB	6.75 KB	0%	2.22 KB
packages/workbox-window/build/workbox-window.dev.umd.js	42.14 KB	42.14 KB	0%	9.36 KB
packages/workbox-window/build/workbox-window.prod.umd.js	4.54 KB	4.54 KB	0%	1.85 KB

Workbox Aggregate Size Plugin

3.54KB gzip'ed (24% of limit)
8.07KB uncompressed

[coveralls]

Coverage remained the same at 79.433% when pulling 8793716 on await-cache-will-update into 8b22c15 on master.