Update import defer tests for evaluation triggers

[nicolo-ribaudo]

Ref #4215.

This updates the tests that check what operations trigger evaluation of deferred modules, based on consensus in the last TC39 meeting. It's effectively what is included in tc39/proposal-defer-import-eval#53.

This PR doesn't include tests about what the results of those operations are (which will need to be tested for .then).

I suggest reviewing commit-by-commit:

• first the first one
• then the last one
• then the second one
• then the third one

All the tests are auto-generated from templates.

There is a bug with templates btw: their desc cannot start with [, because the generator will not escape/prefix it and so it becomes a Yaml array. I had to prefix all the descs with _ for this reason.

[takikawa]

I tried running this in my webkit prototype that's been updated to the new semantics, and as far as I can tell the test cases all run and agree with the implementation.

[ptomato]

There is a bug with templates btw: their desc cannot start with [, because the generator will not escape/prefix it and so it becomes a Yaml array. I had to prefix all the descs with _ for this reason.

I think this is probably working as intended — the .case frontmatter is supposed to be valid YAML, so it wouldn't be escaped, rather parsed and merged into the .template frontmatter. Would it work if you did something like desc: "[[DefineOwnProperty]]"?

[nicolo-ribaudo]

No, because the generator parses that code, finds [[DefineOwnProperty]] as the value of desc, and then creates the generated files without the quotes around it.