Simplify the spawn logic

There was some platform-specific code aimed at very old Node.js versions
we no longer care about.

lib/check-dependencies.js

@@ -24,11 +24,9 @@ const findup = fileName => {
 };
 
 const checkDependenciesHelper = (syncOrAsync, config) => {
-    const spawnShellSupported = semver.satisfies(process.version, '>=4.8.0');
-    const win32 = process.platform === 'win32';
     const output = { log: [], error: [] };
 
-    let packageJson, pkgManagerPath;
+    let packageJson;
 
     let installPromise = Promise.resolve();
     let success = true;
@@ -279,32 +277,14 @@ const checkDependenciesHelper = (syncOrAsync, config) => {
 
         // If we're using a direct path, on Windows we need to invoke it via `node path`, not
         // `cmd /c path`. In UNIX systems we can execute the command directly so no need to wrap.
-        let msg, spawnReturn;
+        let msg;
         const method = syncOrAsync === 'sync' ? spawnSync : spawn;
 
-        if (spawnShellSupported) {
-            spawnReturn = method(`${options.packageManager} install`, {
-                cwd: options.packageDir,
-                stdio: 'inherit',
-                shell: true,
-            });
-        } else if (win32) {
-            spawnReturn = method(
-                pkgManagerPath ? 'node' : 'cmd',
-                pkgManagerPath
-                    ? [pkgManagerPath, 'install']
-                    : ['/c', options.packageManager, 'install'],
-                {
-                    cwd: options.packageDir,
-                    stdio: 'inherit',
-                },
-            );
-        } else {
-            spawnReturn = method(options.packageManager, ['install'], {
-                cwd: options.packageDir,
-                stdio: 'inherit',
-            });
-        }
+        const spawnReturn = method(`${options.packageManager} install`, {
+            cwd: options.packageDir,
+            stdio: 'inherit',
+            shell: true,
+        });
 
         if (syncOrAsync === 'sync') {
             if (spawnReturn.status !== 0) {