esm: drop support for import assertions

This patch removes support for the `assert` keyword
for import attributes. It was an old variant of the
proposal that was only shipped in V8 and no other
engine, and that has then been replaced by the `with`
keyword.

Chrome is planning to remove support for `assert`
in version 126, which will be released in June.

Node.js already supports the `with` keyword for
import attributes, and this patch does not change that.

src/node.cc

@@ -796,19 +796,15 @@ static ExitCode ProcessGlobalArgsInternal(std::vector<std::string>* args,
     return ExitCode::kInvalidCommandLineArgument2;
   }
 
-  // TODO(aduh95): remove this when the harmony-import-assertions flag
-  // is removed in V8.
-  if (std::find(v8_args.begin(), v8_args.end(),
-                "--no-harmony-import-assertions") == v8_args.end()) {
-    v8_args.emplace_back("--harmony-import-assertions");
-  }
   // TODO(aduh95): remove this when the harmony-import-attributes flag
   // is removed in V8.
   if (std::find(v8_args.begin(),
                 v8_args.end(),
                 "--no-harmony-import-attributes") == v8_args.end()) {
     v8_args.emplace_back("--harmony-import-attributes");
   }
+  // TODO(nicolo-ribaudo): remove this once V8 doesn't enable it by default anymore.
+  v8_args.emplace_back("--no-harmony-import-assertions");
 
   auto env_opts = per_process::cli_options->per_isolate->per_env;
   if (std::find(v8_args.begin(), v8_args.end(),

test/es-module/test-esm-import-attributes-errors.js

@@ -55,6 +55,16 @@ async function test() {
     import(jsonModuleDataUrl, { with: { type: 'unsupported' } }),
     { code: 'ERR_IMPORT_ATTRIBUTE_UNSUPPORTED' }
   );
+
+  await rejects(
+    import(jsonModuleDataUrl, { assert: { type: 'json' } }),
+    { code: 'ERR_IMPORT_ATTRIBUTE_MISSING' }
+  );
+
+  await rejects(
+    import(`data:text/javascript,import${JSON.stringify(jsonModuleDataUrl)}assert{type:"json"}`),
+    SyntaxError
+  );
 }
 
 test().then(common.mustCall());

test/es-module/test-esm-import-attributes-errors.mjs

@@ -50,3 +50,13 @@ await rejects(
   import(jsonModuleDataUrl, { with: { type: 'unsupported' } }),
   { code: 'ERR_IMPORT_ATTRIBUTE_UNSUPPORTED' }
 );
+
+await rejects(
+  import(jsonModuleDataUrl, { assert: { type: 'json' } }),
+  { code: 'ERR_IMPORT_ATTRIBUTE_MISSING' }
+);
+
+await rejects(
+  import(`data:text/javascript,import${JSON.stringify(jsonModuleDataUrl)}assert{type:"json"}`),
+  SyntaxError
+);