chore: add test for in-fragment HEAD reflection

[crutchcorn]

Currently, we're doing some dedicated logic inside of next/head to add support for Fragments. However, I noticed there's no dedicated test specifically for this behavior in our tests yet.

This PR simply adds a test for said test case. I plan on doing a follow-up PR to add support for parsing multiple levels of fragments deep (not just one level) and other components

Documentation / Examples

• Make sure the linting passes by running yarn lint

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
buildDuration	15.6s	15.9s	⚠️ +292ms
buildDurationCached	6.1s	6.2s	⚠️ +74ms
nodeModulesSize	378 MB	378 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.174	3.176	0
/ avg req/sec	787.77	787.1	⚠️ -0.67
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.394	1.351	-0.04
/error-in-render avg req/sec	1792.8	1849.91	+57.11

Client Bundles (main, webpack)

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	28 kB	28 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.6 kB	71.6 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	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	2.57 kB	2.57 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.48 kB	5.48 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.26 kB	2.26 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	319 B	319 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	15.2 kB	15.2 kB	✓

Client Build Manifests

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
index.html gzip	531 B	531 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

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
buildDuration	19s	19.2s	⚠️ +180ms
buildDurationCached	6.3s	6.1s	-131ms
nodeModulesSize	378 MB	378 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.167	3.157	-0.01
/ avg req/sec	789.49	791.8	+2.31
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.367	1.359	-0.01
/error-in-render avg req/sec	1829.23	1838.93	+9.7

Client Bundles (main, webpack)

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.3 kB	28.3 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.2 kB	72.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	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	324 B	324 B	✓
dynamic-HASH.js gzip	2.56 kB	2.56 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.59 kB	5.59 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.33 kB	2.33 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	388 B	388 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	15.3 kB	15.3 kB	✓

Client Build Manifests

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
_buildManifest.js gzip	457 B	457 B	✓
Overall change	457 B	457 B	✓

Rendered Page Sizes

	vercel/next.js canary	crutchcorn/next.js head-fragment-reflection-test	Change
index.html gzip	530 B	530 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 338e18a