[dart2wasm] Remove usage of type category table

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>
16 files changed
tree: 8eae7ce9f68c902573daa29f938e9a820b425c99
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. docs/
  6. pkg/
  7. runtime/
  8. samples/
  9. sdk/
  10. tests/
  11. third_party/
  12. tools/
  13. utils/
  14. .clang-format
  15. .gitattributes
  16. .gitconfig
  17. .gitignore
  18. .gn
  19. .mailmap
  20. .style.yapf
  21. AUTHORS
  22. BUILD.gn
  23. CHANGELOG.md
  24. codereview.settings
  25. CONTRIBUTING.md
  26. DEPS
  27. LICENSE
  28. OWNERS
  29. PATENT_GRANT
  30. PRESUBMIT.py
  31. README.dart-sdk
  32. README.md
  33. sdk.code-workspace
  34. sdk_args.gni
  35. SECURITY.md
  36. WATCHLISTS
README.md

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