[dart2wasm] Add BoxedInt immutable array cache to support dart:convert.

https://github.com/dart-lang/sdk/blob/main/sdk/lib/_internal/wasm/lib/convert_patch.dart#L1110

Change-Id: I00fb812af9818c566e72360b5744699a50e3eb67
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/412860
Commit-Queue: Nate Biggs <[email protected]>
Reviewed-by: Martin Kustermann <[email protected]>

Author: natebiggs

pkg/dart2wasm/lib/kernel_nodes.dart

@@ -428,6 +428,8 @@ mixin KernelNodes {
       index.getTopLevelField('dart:_internal', 'i32ConstArray');
   late final Field i64ConstImmutableArrayCache =
       index.getTopLevelField('dart:_internal', 'i64ConstImmutableArray');
+  late final Field boxedIntImmutableArrayCache =
+      index.getTopLevelField('dart:_internal', 'boxedIntImmutableArray');
 
   // Debugging
   late final Procedure printToConsole =
@@ -450,6 +452,7 @@ mixin KernelNodes {
     _makeElementType(coreTypes.stringClass): stringConstImmutableArrayCache,
     _makeElementType(wasmI8Class): i8ConstImmutableArrayCache,
     _makeElementType(wasmI64Class): i64ConstImmutableArrayCache,
+    _makeElementType(boxedIntClass): boxedIntImmutableArrayCache,
   };
 
   InterfaceType _makeElementType(Class c,

sdk/lib/_internal/wasm/lib/dynamic_module.dart

@@ -113,6 +113,8 @@ final i8ConstImmutableArray = WasmArrayConstCache();
 final i32ConstArray = WasmArrayConstCache();
 @pragma('dyn-module:callable')
 final i64ConstImmutableArray = WasmArrayConstCache();
+@pragma('dyn-module:callable')
+final boxedIntImmutableArray = WasmArrayConstCache();
 
 class WasmArrayConstCache {
   // Guaranteed by construction to contain only arrays with the same type.