fix: load node even if frame has opener

[alexstrat]

Description of Change

Fixes #18070
Load Node in renderer frame even if it has an opener.

Test instructions

$ git clone git@github.com:jeremyspiegel/electron-quick-start.git -b preload-not-run-on-window-open
$ cd electron-quick-start
$ npm install
$ /path/to/out/out/Debug/Electron.app/Contents/MacOS/Electron .

Verify that an alert 'preload' is shown in opened window.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed preload script not executed in a window created after window.open

cc @jeremyspiegel

[alexstrat]

Obviously, I bumped into #15213 and #12634 that I originally missed.

In the current state, this PR introduces a memory leak as described in #12634. I was not able to get rid of it even with calling node::FreeEnvironment(env) in WillReleaseScriptContext like done when nodeIntegrationInSubframes is enabled. (it BTW makes me think that nodeIntegrationInSubframes probably causes the same memory leaks described in #12634 but with iframes).

So I'll just close this PR and simply suggest precisions of documentation in #18156.