tools: enable no-return-await lint rule

.eslintrc.yaml

@@ -69,6 +69,7 @@ rules:
       message: __defineGetter__ is deprecated.
     - property: __defineSetter__
       message: __defineSetter__ is deprecated.
+  no-return-await: error
   no-self-assign: error
   no-throw-literal: error
   no-unused-labels: error

doc/api/util.md

@@ -31,7 +31,7 @@ For example:
 const util = require('util');
 
 async function fn() {
-  return await Promise.resolve('hello world');
+  return 'hello world';
 }
 const callbackFunction = util.callbackify(fn);
 

test/common/inspector-helper.js

@@ -390,7 +390,7 @@ class NodeInstance {
     console.log('[test]', 'Connecting to a child Node process');
     const response = await this.httpGet(null, '/json/list');
     const url = response[0]['webSocketDebuggerUrl'];
-    return await this.wsHandshake(url);
+    return this.wsHandshake(url);
   }
 
   expectShutdown() {

test/parallel/test-util-callbackify.js

@@ -28,7 +28,7 @@ const values = [
   for (const value of values) {
     // Test and `async function`
     async function asyncFn() {
-      return await Promise.resolve(value);
+      return value;
     }
 
     const cbAsyncFn = callbackify(asyncFn);
@@ -70,7 +70,7 @@ const values = [
   for (const value of values) {
     // Test an `async function`
     async function asyncFn() {
-      return await Promise.reject(value);
+      return Promise.reject(value);
     }
 
     const cbAsyncFn = callbackify(asyncFn);
@@ -142,7 +142,7 @@ const values = [
   for (const value of values) {
     async function asyncFn(arg) {
       assert.strictEqual(arg, value);
-      return await Promise.resolve(arg);
+      return arg;
     }
 
     const cbAsyncFn = callbackify(asyncFn);
@@ -183,7 +183,7 @@ const values = [
     const iAmThat = {
       async fn(arg) {
         assert.strictEqual(this, iAmThat);
-        return await Promise.resolve(arg);
+        return arg;
       },
     };
     iAmThat.cbFn = callbackify(iAmThat.fn);
@@ -241,7 +241,7 @@ const values = [
 
 {
   async function asyncFn() {
-    return await Promise.resolve(42);
+    return 42;
   }
 
   const cb = callbackify(asyncFn);