[dart2wasm] Emit nominal types and don't use RTTs by default.

This enables us to upgrade our testing to use a newer version of d8.

Change-Id: I79a8879a325b9996b9923304439a3ee8fa5fa02a
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-debug-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238345
Reviewed-by: Joshua Litt <[email protected]>
Commit-Queue: Aske Simon Christensen <[email protected]>

Author: askeksa

pkg/dart2wasm/dart2wasm.md

@@ -16,12 +16,12 @@ where *options* include:
 | `--`[`no-`]`lazy-constants`             | no      | Instantiate constants lazily.
 | `--`[`no-`]`local-nullability`          | no      | Use non-nullable types for non-nullable locals and temporaries.
 | `--`[`no-`]`name-section`               | yes     | Emit Name Section with function names.
-| `--`[`no-`]`nominal-types`              | no      | Emit experimental nominal types.
+| `--`[`no-`]`nominal-types`              | yes     | Emit nominal types.
 | `--`[`no-`]`parameter-nullability`      | yes     | Use non-nullable types for non-nullable parameters and return values.
 | `--`[`no-`]`polymorphic-specialization` | no      | Do virtual calls by switching on the class ID instead of using `call_indirect`.
 | `--`[`no-`]`print-kernel`               | no      | Print IR for each function before compiling it.
 | `--`[`no-`]`print-wasm`                 | no      | Print Wasm instructions of each compiled function.
-| `--`[`no-`]`runtime-types`              | yes     | Use RTTs for allocations and casts.
+| `--`[`no-`]`runtime-types`              | no      | Use RTTs for allocations and casts.
 | `--`[`no-`]`string-data-segments`       | no      | Use experimental array init from data segment for string constants.
 | `--watch` *offset*                      |         | Print stack trace leading to the byte at offset *offset* in the `.wasm` output file. Can be specified multiple times.
 

pkg/dart2wasm/lib/translator.dart

@@ -32,12 +32,12 @@ class TranslatorOptions {
   bool lazyConstants = false;
   bool localNullability = false;
   bool nameSection = true;
-  bool nominalTypes = false;
+  bool nominalTypes = true;
   bool parameterNullability = true;
   bool polymorphicSpecialization = false;
   bool printKernel = false;
   bool printWasm = false;
-  bool runtimeTypes = true;
+  bool runtimeTypes = false;
   bool stringDataSegments = false;
   List<int>? watchPoints = null;