Exact normative requirements for interface definitions are unclear #732
Description
The Streams standard doesn't use Web IDL to define APIs, unlike many other WHATWG Standards. Instead, it defines interfaces with an introduction like this:
"If one were to write the ReadableStream class in something close to the syntax of [ECMASCRIPT]"
Followed by text that's vaguely similar to ECMAScript code (but in many cases not actually syntactically valid as such).
There doesn't seem to be a definition anywhere of the processing requirements for this quasi-ECMAScript syntax. In the case of Web IDL, all details are precisely defined, including corner cases, and often subtle details have been relevant to interoperability. In theory, an overly literal-minded person could claim that the "if one were to write" sentence imposes no normative requirements at all. In practice, browsers could easily interpret quasi-ECMAScript definitions in subtly different ways that affect interop down the line.
Please either define the quasi-ECMAScript syntax and its processing requirements to a similar level as has been done for Web IDL, or switch to Web IDL instead.