Ensure there is only 1 render pass in concurrent rendering with getInitialProps in _document

[shuding]

This PR makes sure renderPage calls renderShell in concurrent features, and renderToString if not.

Closes #36268, #36229.

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running yarn lint

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js shu/8eac	Change
buildDuration	18.7s	18.7s	⚠️ +51ms
buildDurationCached	7.1s	7s	-64ms
nodeModulesSize	481 MB	481 MB	⚠️ +2.22 kB

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js shu/8eac	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.091	4.138	⚠️ +0.05
/ avg req/sec	611.12	604.16	⚠️ -6.96
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.042	2.023	-0.02
/error-in-render avg req/sec	1224.37	1235.69	+11.32

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js shu/8eac	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	28.5 kB	28.5 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.1 kB	72.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js shu/8eac	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js shu/8eac	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	192 B	192 B	✓
amp-HASH.js gzip	309 B	309 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	3.04 kB	3.04 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.74 kB	5.74 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.36 kB	2.36 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	392 B	392 B	✓
withRouter-HASH.js gzip	319 B	319 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16 kB	16 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js shu/8eac	Change
_buildManifest.js gzip	461 B	461 B	✓
Overall change	461 B	461 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js shu/8eac	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 increase ⚠️

	vercel/next.js canary	vercel/next.js shu/8eac	Change
buildDuration	21.4s	21.5s	⚠️ +156ms
buildDurationCached	7.4s	7.1s	-254ms
nodeModulesSize	481 MB	481 MB	⚠️ +2.22 kB

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js shu/8eac	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.119	4.022	-0.1
/ avg req/sec	607.01	621.62	+14.61
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.098	2.087	-0.01
/error-in-render avg req/sec	1191.47	1198.02	+6.55

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js shu/8eac	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.9 kB	28.9 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.8 kB	72.8 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js shu/8eac	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js shu/8eac	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	313 B	313 B	✓
css-HASH.js gzip	325 B	325 B	✓
dynamic-HASH.js gzip	3.02 kB	3.02 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.79 kB	5.79 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.44 kB	2.44 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	393 B	393 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.1 kB	16.1 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js shu/8eac	Change
_buildManifest.js gzip	457 B	457 B	✓
Overall change	457 B	457 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js shu/8eac	Change
index.html gzip	532 B	532 B	✓
link.html gzip	546 B	546 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 7a1ee74