fix: preserve order of link tags on HMR

[guansss]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

Resolves 959
Resolves #955

Problem:

Say there are two CSS chunks in sequence: A and B, the generated link tags appear like:

A.css
B.css

When A is modified, the HMR handler will append its new link tag to document.head, resulting in a different order:

B.css
A.css'

Now the order is incorrect - A's styles will override B's.

Solution:

Insert new link tag right after the old one, so that the result will be correct:

A.css'
B.css

I had no clue on how to add a test for this, 🤔 so I just updated the manual test, hope that's valid.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: guansss / name: Guan (b9cf364)

[guansss]

Hi @alexander-akait , could you please have a look at this?

[alexander-akait]

@guansss Yeah, in my todo (just a lot of issues), will look tomorrow

[alexander-akait]

Looks good

[alexander-akait]

Can you update tests? Need to copy some files from test/fixtures/js to own tests

[guansss]

OK, updated.

[alexander-akait]

Thank you

[guansss]

Hmm, there was an extra blank line generated while running tests on my machine, not sure why.

[codecov]

Codecov Report

Base: 90.37% // Head: 90.37% // No change to project coverage 👍

Coverage data is based on head (b8e28dc) compared to base (2633446).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #982   +/-   ##
=======================================
  Coverage   90.37%   90.37%           
=======================================
  Files           5        5           
  Lines         831      831           
  Branches      222      222           
=======================================
  Hits          751      751           
  Misses         70       70           
  Partials       10       10           

Impacted Files	Coverage Δ
src/index.js	96.30% <100.00%> (ø)

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[alexander-akait]

I have tested your solution with #959 and looks like it doesn't work, because order after HTML extraction is different

[guansss]

Oops, the issue I expected to solve is #955, I linked a wrong one, sorry for wasting your time to test on it :(

[guansss]

Updated files for old API test.