fix(Collapse): fix nested collapse icon

[jdkahn]

No description provided.

[codecov]

Codecov Report

Merging #421 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #421      +/-   ##
==========================================
+ Coverage   90.82%   90.83%   +<.01%     
==========================================
  Files         241      241              
  Lines       13500    13501       +1     
  Branches     4160     4160              
==========================================
+ Hits        12262    12263       +1     
  Misses       1220     1220              
  Partials       18       18

Impacted Files	Coverage Δ
src/collapse/panel.jsx	100% <100%> (ø)	⬆️

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[youluna]

@tao1991123 please check this carefully! Will the PR have any bad impact on users? Someone who uses old css stylesheet and new js files

[jdkahn]

@tao1991123 Is it possible to do that? Wouldn't users have to use both styles and js files from the same version?

[youluna]

Wouldn't users have to use both styles and js files from the same version?

No, they don't. Users who use theme package( https://github.com/alibaba-fusion/next/blob/master/site/en-us/theme.md ) use both @alifd/next and @alifd/theme-xxx as their dependencies. @alifd/theme-xxx is generated based on a specific version of @alifd/next. @alifd/theme-xxx is published by users via Config Platform (fusion.design). The publish of @alifd/theme-xxx is less frequent than @alifd/next.

So version of css will always older than the js version( among the same minor verison ). Many users use it this way.

Users should keep css and js version in the same minor version.
e.g.
1.12.2 css with 1.12.2 js ---> Fusion ensure it works.
1.12.2 css with 1.12.6 js ---> Fusion ensure it works.
1.12.2 css with 1.13.6 js ---> Users should update the theme package

[tao1991123]

@youluna means user writes css styles to overwrite the default style.

Only one case that users overwrite

.panel-expanded .icon {
xxxxx
}

but new style is priorer than the old

.panel .icon.icon-expand {
xxxx
}

I reviewed and I think it's ok, you remove none of old classnames, it compatible.
I mean there is nearly no user who did this.

so I approved

[tao1991123]

OK

[youluna]

close #416