Modify Babel React JSX Duplicate Children Fix

[lunaruan]

If a JSX element has both a children prop and children (ie. <div children={childOne}>{childTwo}</div>), IE throws an Multiple definitions of a property not allowed in strict mode. This modifies the previous fix (which used an Object.assign) by making the duplicate children a sequence expression on the next prop/child instead so that ordering is preserved. For example:

<Component children={useA()} foo={useB()} children={useC()}>{useD()}</Component>

should compile to

React.jsx(Component, {foo: (useA(), useB()), children: (useC(), useD)})

[sizebot]

No significant bundle size changes to report.

Generated by 🚫 dangerJS against 07b0a15

[trueadm]

The ordering and sequencing of calls is extremely important, especially because of hooks. Judging by the summar, this approach is likely to lead to the wrong sequencing order, which means that hook calls (when minified) will be out-of-order:

For example:

<Component children={useA()} foo={useB()} children={useC()}>{useD()}</Component>

[trueadm]

Actually, I think the summary of this PR is somewhat different from the implementation. @lunaruan helped by explaining my case and looking into the implementation, this seems to be a non-issue. Sorry for the confusion and great stuff! :)