[bug] super constructors don't work with Custom Elements v1

[trusktr]

Buble compiles super() calls to something like ParentClass.call(this).

This causes any and all Custom Elements (v1) to not work because they require the use of new (ES2015 classes), with an error like the following in Chrome:

Uncaught TypeError: Failed to construct 'HTMLElement': Please use the 'new' operator, this DOM object constructor cannot be called as a function

For example, see this output.

Try to run the output code in your browser, and you'll get the error.

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Hmm, I don't think this is a bug with Buble. It's just not possible to compile anything for Custom Elements v1 to ES5 it seems. :(

This is a bug with Custom Elements v1 and it being designed for future browsers in a way that is impossible to transpile downward.

[trusktr]

Unfortunately, the only solution that would sort of work is to use Refelct.construct, but that is only supported in Edge 12+.

[trusktr]

@justinfagnani made this incredible hack which makes transpiled code work in older browsers! https://github.com/trusktr/custom-elements-1/blob/3984e69c85376d36d83b8a602cc5202c1edd9eed/src/native-shim.js

To be specific, that one makes transpiled code work in IE11. For IE10, let, const, and Map needs to be replaced by ES5 equivalents then it will work.

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Sorry for the red flag here!