Fix ensurePage race condition

[ijjk]

This fixes a race condition I noticed while working on the tests in #28634 where when ensurePage is called it can resolve before the assets are actually emitted causing an unexpected 404 for page bundles in development. This was causing instability while running the tests since some tests ensure a full navigation doesn't occur and it was from the page bundle not being available yet.

It seems when done is fired for the current compilation in development it includes all entrypoints even if they haven't been emitted yet and are queued for the next invalidation so this resolves the race condition by waiting to resolve ensurePage until after the queued build is complete.

Also found an invalid test in the basePath suite causing incorrect failures/successes from a check not being awaited which is being skipped in this PR to prevent an incorrect failure as the behavior being tested doesn't seem to follow the test.

This might also explain the issues relating to unexpected hard navigations in development that were still occurring after the route-loader timeout was updated in development.

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
buildDuration	11.9s	11.5s	-389ms
buildDurationCached	3.1s	3s	-55ms
nodeModulesSize	48.2 MB	48.2 MB	⚠️ +254 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.255	2.285	⚠️ +0.03
/ avg req/sec	1108.71	1093.98	⚠️ -14.73
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.273	1.162	-0.11
/error-in-render avg req/sec	1963.46	2152.31	+188.85

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
745.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	23.3 kB	23.3 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	67.2 kB	67.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
_app-HASH.js gzip	979 B	979 B	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.67 kB	2.67 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	918 B	918 B	✓
image-HASH.js gzip	4.14 kB	4.14 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	318 B	318 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	13 kB	13 kB	✓

Client Build Manifests

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
_buildManifest.js gzip	492 B	492 B	✓
Overall change	492 B	492 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
index.html gzip	539 B	539 B	✓
link.html gzip	552 B	552 B	✓
withRouter.html gzip	533 B	533 B	✓
Overall change	1.62 kB	1.62 kB	✓

---

Webpack 4 Mode (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
buildDuration	9.1s	9.5s	⚠️ +431ms
buildDurationCached	3.9s	4s	⚠️ +132ms
nodeModulesSize	48.2 MB	48.2 MB	⚠️ +254 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.165	2.376	⚠️ +0.21
/ avg req/sec	1154.79	1052	⚠️ -102.79
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.241	1.304	⚠️ +0.06
/error-in-render avg req/sec	2013.83	1916.5	⚠️ -97.33

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
16.HASH.js gzip	186 B	186 B	✓
677f882d2ed8..HASH.js gzip	14.1 kB	14.1 kB	✓
framework.HASH.js gzip	41.9 kB	41.9 kB	✓
main-HASH.js gzip	10.7 kB	10.7 kB	✓
webpack-HASH.js gzip	1.19 kB	1.19 kB	✓
Overall change	68.1 kB	68.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
_app-HASH.js gzip	964 B	964 B	✓
_error-HASH.js gzip	3.8 kB	3.8 kB	✓
amp-HASH.js gzip	552 B	552 B	✓
css-HASH.js gzip	333 B	333 B	✓
dynamic-HASH.js gzip	2.87 kB	2.87 kB	✓
head-HASH.js gzip	3.06 kB	3.06 kB	✓
hooks-HASH.js gzip	924 B	924 B	✓
index-HASH.js gzip	231 B	231 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	298 B	298 B	✓
script-HASH.js gzip	3.03 kB	3.03 kB	✓
withRouter-HASH.js gzip	295 B	295 B	✓
30809af5c834..565.css gzip	125 B	125 B	✓
Overall change	18.1 kB	18.1 kB	✓

Client Build Manifests

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
_buildManifest.js gzip	500 B	500 B	✓
Overall change	500 B	500 B	✓

Rendered Page Sizes

	vercel/next.js canary	ijjk/next.js fix/dev-race-condition	Change
index.html gzip	585 B	585 B	✓
link.html gzip	597 B	597 B	✓
withRouter.html gzip	578 B	578 B	✓
Overall change	1.76 kB	1.76 kB	✓

Commit: 969ed2d