fix(Menu): child-selected should work in popup mode

[youluna]

No description provided.

[codecov]

Codecov Report

Merging #999 into master will decrease coverage by 0.01%.
The diff coverage is 78.94%.

@@            Coverage Diff             @@
##           master     #999      +/-   ##
==========================================
- Coverage   91.44%   91.43%   -0.02%     
==========================================
  Files         247      247              
  Lines       14406    14415       +9     
  Branches     4558     4563       +5     
==========================================
+ Hits        13174    13180       +6     
- Misses       1213     1216       +3     
  Partials       19       19

Impacted Files	Coverage Δ
src/menu/view/popup-item.jsx	92.79% <100%> (+0.48%)	⬆️
src/menu/view/sub-menu.jsx	93.54% <100%> (ø)	⬆️
src/menu/view/menu.jsx	89.15% <50%> (-0.75%)	⬇️

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[myronliu347]

单测不通过看下