Remove useMaybeDeferContent hook

[devknoll]

This was added for the previous iteration of the streaming getServerSideProps RFC, but is no longer needed, so it can be removed.

Note: make sure you view the diff without whitespace for clarity.

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
buildDuration	16.9s	16.3s	-554ms
buildDurationCached	6.3s	6.2s	-76ms
nodeModulesSize	359 MB	359 MB	-3.73 kB

Page Load Tests Overall increase ✓

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.121	3.017	-0.1
/ avg req/sec	800.98	828.69	+27.71
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.447	1.399	-0.05
/error-in-render avg req/sec	1727.69	1787.13	+59.44

Client Bundles (main, webpack, commons)

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	27.9 kB	27.9 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.5 kB	71.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	326 B	326 B	✓
dynamic-HASH.js gzip	2.57 kB	2.57 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	919 B	919 B	✓
image-HASH.js gzip	5.05 kB	5.05 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.26 kB	2.26 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.7 kB	14.7 kB	✓

Client Build Manifests

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
buildDuration	20s	20.1s	⚠️ +167ms
buildDurationCached	6.3s	6.2s	-80ms
nodeModulesSize	359 MB	359 MB	-3.73 kB

Page Load Tests Overall increase ✓

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.203	3.098	-0.1
/ avg req/sec	780.61	807.05	+26.44
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.451	1.444	-0.01
/error-in-render avg req/sec	1722.59	1731.2	+8.61

Client Bundles (main, webpack, commons)

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.1 kB	42.1 kB	✓
main-HASH.js gzip	27.9 kB	27.9 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.7 kB	71.7 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.56 kB	2.56 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	911 B	911 B	✓
image-HASH.js gzip	5.08 kB	5.08 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.28 kB	2.28 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.7 kB	14.7 kB	✓

Client Build Manifests

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	azukaru/next.js x-rm-use-deferred-content-hook	Change
index.html gzip	533 B	533 B	✓
link.html gzip	547 B	547 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.61 kB	1.61 kB	✓

Commit: 1e59b09