Throw error if specific constructors are called as plain functions

[JakeChampion]

The below constructors will now throw an error if called as plain functions as per their specifications:

• CompressionStream
• Headers
• Request
• Response
• TextDecoder
• TextEncoder
• TransformStream
• URL
• URLSearchParams

These constructors can now only be called via new or Reflect.construct

I wasn't sure what we want to do with the Fastly specific constructors such as CacheOverride so I have left them as-is

[JakeChampion]

I thought this would increase the amount of passed tests from web-platform-tests but it looks like this part of the WebIDL specification wasn't being fully tested within web-platform-tests.

I've made a pull-request to web-platform-tests which tests this part, if/when that gets merged I can update our version of web-platform-tests and then see how many more tests we pass 👍

[tschneidereit]

This is great, thank you!

I have two notes that should be fairly simple to address before landing this:

1. I think we should apply this to Fastly-specific constructors as well
2. how would you feel about introducing a CTOR_HEADER macro, parallel to the METHOD_HEADER one, and using that instead?

The obvious difference is that we can't infer the name to use from __func__, but that seems ok to me.

[JakeChampion]

This is great, thank you!

I have two notes that should be fairly simple to address before landing this:

1. I think we should apply this to Fastly-specific constructors as well

2. how would you feel about introducing a `CTOR_HEADER` macro, parallel to the `METHOD_HEADER` one, and using that instead?

The obvious difference is that we can't infer the name to use from __func__, but that seems ok to me.

Oh that is a good suggestion! ☺️
I've made those changes and pushed it up now 👍

[tschneidereit]

Thank you!

[tschneidereit]

Oh, turns out URLSearchParams doesn't require any arguments, so we have a bunch of test failures :)

[JakeChampion]

Oh, turns out URLSearchParams doesn't require any arguments, so we have a bunch of test failures :)

Hooray for tests! 👯

[tschneidereit]

Hooray for tests! 👯

Indeed!