wasi: drop --experimental-wasm-bigint requirement

After the V8 8.5 update, the WASI APIs no longer require the
use of --experimental-wasm-bigint. This commit removes its use.

PR-URL: #35415
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

Author: cjihrig

doc/api/wasi.md

@@ -70,8 +70,8 @@ Use [wabt](https://github.com/WebAssembly/wabt) to compile `.wat` to `.wasm`
 $ wat2wasm demo.wat
 ```
 
-The `--experimental-wasi-unstable-preview1` and `--experimental-wasm-bigint`
-CLI arguments are needed for this example to run.
+The `--experimental-wasi-unstable-preview1` CLI argument is needed for this
+example to run.
 
 ## Class: `WASI`
 <!-- YAML

test/wasi/test-return-on-exit.js

@@ -1,4 +1,4 @@
-// Flags: --experimental-wasi-unstable-preview1 --experimental-wasm-bigint
+// Flags: --experimental-wasi-unstable-preview1
 'use strict';
 const common = require('../common');
 const assert = require('assert');

test/wasi/test-wasi-not-started.js

@@ -29,7 +29,6 @@ if (process.argv[2] === 'wasi-child') {
 
   const child = cp.spawnSync(process.execPath, [
     '--experimental-wasi-unstable-preview1',
-    '--experimental-wasm-bigint',
     __filename,
     'wasi-child'
   ], {

test/wasi/test-wasi-stdio.js

@@ -1,4 +1,4 @@
-// Flags: --experimental-wasi-unstable-preview1 --experimental-wasm-bigint
+// Flags: --experimental-wasi-unstable-preview1
 'use strict';
 const common = require('../common');
 const tmpdir = require('../common/tmpdir');

test/wasi/test-wasi-symlinks.js

@@ -62,7 +62,6 @@ if (process.argv[2] === 'wasi-child') {
     const opts = { env: { ...process.env, NODE_DEBUG_NATIVE: 'wasi' } };
     const child = cp.spawnSync(process.execPath, [
       '--experimental-wasi-unstable-preview1',
-      '--experimental-wasm-bigint',
       __filename,
       'wasi-child',
       options.test,

test/wasi/test-wasi.js

@@ -51,7 +51,6 @@ if (process.argv[2] === 'wasi-child') {
 
     const child = cp.spawnSync(process.execPath, [
       '--experimental-wasi-unstable-preview1',
-      '--experimental-wasm-bigint',
       __filename,
       'wasi-child',
       options.test