fix(ext/node): handle node child_process with --v8-options flag

Makes `v8flags` package from NPM work.

ext/node/polyfills/internal/child_process.ts

@@ -1030,6 +1030,7 @@ const kNodeFlagsMap = new Map([
   ["--v8-pool-size", kLongArg],
 ]);
 const kDenoSubcommands = new Set([
+  "add",
   "bench",
   "bundle",
   "cache",
@@ -1046,6 +1047,7 @@ const kDenoSubcommands = new Set([
   "install",
   "lint",
   "lsp",
+  "publish",
   "repl",
   "run",
   "tasks",
@@ -1092,6 +1094,12 @@ function toDenoArgs(args: string[]): string[] {
     let isLongWithValue = false;
     let flagValue;
 
+    if (flag === "--v8-options") {
+      // If --v8-options is passed, it should be replaced with --v8-flags="--help".
+      denoArgs.push("--v8-flags=--help");
+      continue;
+    }
+
     if (flagInfo === undefined) {
       // If the flag was not found, it's either not a known flag or it's a long
       // flag containing an '='.

tests/integration/npm_tests.rs

@@ -2930,3 +2930,11 @@ async fn test_private_npm_registry() {
   let resp = client.execute(req).await.unwrap();
   assert_eq!(resp.status(), reqwest::StatusCode::OK);
 }
+
+itest!(v8flags {
+  args: "run -A npm/v8flags/main.js",
+  output: "npm/v8flags/main.out",
+  envs: env_vars_for_npm_tests(),
+  exit_code: 0,
+  http_server: true,
+});

tests/testdata/npm/v8flags/main.js

@@ -0,0 +1,17 @@
+import v8flags from "npm:v8flags@4.0.1";
+
+const flags = await new Promise((resolve, reject) => {
+  v8flags((err, flags) => {
+    if (err) {
+      reject(err);
+    } else {
+      resolve(flags);
+    }
+  });
+});
+
+if (flags.length < 100) {
+  throw new Error("Expected at least 100 flags");
+}
+
+console.log("ok");

tests/testdata/npm/v8flags/main.out

@@ -0,0 +1,3 @@
+Download http://localhost:4260/v8flags
+Download http://localhost:4260/v8flags/v8flags-4.0.1.tgz
+ok