The type category table is a O(number-of-classes) sized byte array that
maps from class-id to either a type category (function, record, ...) or
a masqueraded class-id.
* for flute this table takes up around 1 KB.
* this prevents from making concrete class-ids come before all abstract
class ids
After recent changes the core RTT implementation no longer involves
masqueraded types (i.e. `<obj> is/as <type>` and `<type> <: <type>`
queries don't trigger masquerading functionality)
This CL removes the type category table, the special casing in the
class-id assignment and the compiler support for building the table.
Instead we move the logic to pure dart code, which can use normal `is`
checks to perform its function.
We add one optimization: The compiler will provide the class-id from
which one only non-masqueraded classes come. This makes the masquerading
function have a fast path.
* We use `Wasm{TypedData,String}Base` marker interfaces i
`dart:_internal` to check for wasm-backed implementations
* We use `-Ddart.wasm.js_compatibility` to provide JSCM mode
We add a test that actually exercises the 2 modes.
Change-Id: I051c35b17878950402a1336df871a686b649f732
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/349641
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
