Fix for #893 issue

[westtrade]

In some case in this place, without this check, delete will remove necessary numeric keys. This is a possible fix for #893 issue

[coveralls]

Coverage increased (+0.02%) to 90.265% when pulling 1800cb8 on westtrade:patch-3 into 26ab32f on marko-js:master.

[codecov]

Codecov Report

Merging #894 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #894      +/-   ##
==========================================
+ Coverage   90.24%   90.26%   +0.01%     
==========================================
  Files         311      311              
  Lines       11319    11320       +1     
==========================================
+ Hits        10215    10218       +3     
+ Misses       1104     1102       -2

Impacted Files	Coverage Δ
src/components/util-browser.js	100% <100%> (ø)	⬆️
src/runtime/html/AsyncStream.js	87.65% <0%> (+0.82%)	⬆️

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[patrick-steele-idem]

Thank you for filing the issue and creating this PR. I was able to reproduce the problem, but it was not simple since I needed to assign the same key to different elements in the template and those different elements needed to have different tag names. Here is the test case I added: https://github.com/marko-js/marko/tree/master/test/autotests/components-browser/event-handler-non-bubbling-rerender-el-mismatch

The problem was that we add elements to the keyed lookup during diffing, but we defer destroying until after DOM diffing is completed. Because destroying happens later, a destroyed node with a key that matches an incompatible (i.e., different tag name) would cause the new keyed element to be deleted from the keyed lookup. Your fix solves the problem. Thank you! 👍

I've merging this PR, but I'm surprised you ran into the issue. New version published:

+ marko@4.5.1