dependencies(vue): Update vue-loader to 15.x.x

[pksunkara]

Fixes #3509, #3492

[codecov]

Codecov Report

Merging #3911 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #3911      +/-   ##
==========================================
- Coverage   41.56%   41.55%   -0.01%     
==========================================
  Files         455      455              
  Lines        5178     5179       +1     
  Branches      899      899              
==========================================
  Hits         2152     2152              
- Misses       2486     2487       +1     
  Partials      540      540

Impacted Files	Coverage Δ
app/vue/src/server/wrapInitialConfig.js	0% <0%> (ø)	⬆️

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[igor-dv]

Thanks!

Looks a reasonable change, since we are preparing a breaking version of Storybook.

Any reason why the visual tests could fail, though?

[pksunkara]

I don't have any idea on why that is. I didn't dig deep because it was just a <h1> style change. Maybe the browser in chromatic changed. Do you want me to find out why this is happening?

[pksunkara]

Actually, found out why this is happening. You can see h1 having font-weight: normal at https://github.com/storybooks/storybook/blob/83d55c23fa124fa87cd061bdb5b5ce9453b393c1/examples/vue-kitchen-sink/src/App.vue#L43-L45 But before this PR, this wasn't being used by the component Welcome. The font-weight: bold from the user-agent was being used.

So, I guess, this PR kinda fixes the behaviour now.

[igor-dv]

I don't understand how changing the vue-loader version fixes this

[pksunkara]

https://vue-loader.vuejs.org/migrating.html#style-injection
vuejs/vue-loader@234d48b

[igor-dv]

Ah, thanks, got it.

[igor-dv]

@storybooks/team, speak now or forever hold your peace

[ndelangen]

Absolutely perfect!