onScriptComplete is not defined under Firefox 40

[aleen42]

Bug report

What is the current behavior?

During bootstrap, onScriptComplete has an error script when runing under Firefox 40+

If the current behavior is a bug, please provide the POC.

Error script was thrown by the script generated by lib/web/JsonpMainTemplatePlugin.js.

I have tested that it did not seem the problem of hoisted, as the following snippet has worked under Firefox 40:

(function () {
    console.log(test);
    function test() {}
})();

The real reason is that function onScriptComplete has been declared inside a condition block rather than a function block (As a common sense, functions declaration must be placed at the root of a function block, no-inner-declaration):

if (true) {
    /** throw an error: func is not defined */
    console.log(func);
    function func () {}
}

Other relevant information:
webpack version: 4.4.1
Node.js version: v7.10.1
Operating System: Windows 10

[aleen42]

Someones has created a PR before, #7210, which resolution seems wrong. And is it necessary to create another PR?

[alexander-akait]

@aleen42 feel free to send pr

[aleen42]

The PR #7210 has been waited for merging, and what is the current stage? If it is merged, this issue can be solved at the same time. @