lib: simplify the readonly properties of icu

Call Object.defineProperty() twice to set readonly property is
unnecessary.

lib/internal/bootstrap_node.js

@@ -440,28 +440,13 @@
     // of possible types.
     const versionTypes = icu.getVersion().split(',');
 
-    function makeGetter(name) {
-      return () => {
-        // With an argument, getVersion(type) returns
-        // the actual version string.
-        const version = icu.getVersion(name);
-        // Replace the current getter with a new property.
-        delete process.versions[name];
-        Object.defineProperty(process.versions, name, {
-          value: version,
-          writable: false,
-          enumerable: true
-        });
-        return version;
-      };
-    }
-
     for (var n = 0; n < versionTypes.length; n++) {
       var name = versionTypes[n];
+      const version = icu.getVersion(name);
       Object.defineProperty(process.versions, name, {
-        configurable: true,
+        writable: false,
         enumerable: true,
-        get: makeGetter(name)
+        value: version
       });
     }
   }

test/parallel/test-process-versions.js

@@ -32,3 +32,9 @@ assert(commonTemplate.test(process.versions.zlib));
 assert(/^\d+\.\d+\.\d+(?:\.\d+)?(?: \(candidate\))?$/
   .test(process.versions.v8));
 assert(/^\d+$/.test(process.versions.modules));
+
+for (let i = 0; i < expected_keys.length; i++) {
+  const key = expected_keys[i];
+  const descriptor = Object.getOwnPropertyDescriptor(process.versions, key);
+  assert.strictEqual(descriptor.writable, false);
+}