test,lib,doc: use function declarations

Replace function expressions with function declarations in preparation
for a lint rule requiring function declarations.

Backport-PR-URL: #19447
PR-URL: #12711
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

test/addons-napi/test_async/test.js

@@ -6,8 +6,7 @@ const test_async = require(`./build/${common.buildType}/test_async`);
 test_async.Test(5, common.mustCall(function(err, val) {
   assert.strictEqual(err, null);
   assert.strictEqual(val, 10);
-  process.nextTick(common.mustCall(function() {}));
+  process.nextTick(common.mustCall());
 }));
 
-const cancelSuceeded = function() {};
-test_async.TestCancel(common.mustCall(cancelSuceeded));
+test_async.TestCancel(common.mustCall());

test/addons-napi/test_exception/test.js

@@ -4,12 +4,12 @@ const common = require('../../common');
 const test_exception = require(`./build/${common.buildType}/test_exception`);
 const assert = require('assert');
 const theError = new Error('Some error');
-const throwTheError = function() {
+function throwTheError() {
   throw theError;
-};
+}
 let caughtError;
 
-const throwNoError = function() {};
+const throwNoError = common.noop;
 
 // Test that the native side successfully captures the exception
 let returnedError = test_exception.returnException(throwTheError);

test/addons-napi/test_instanceof/test.js

@@ -57,14 +57,14 @@ if (typeof Symbol !== 'undefined' && 'hasInstance' in Symbol &&
       (theObject instanceof theConstructor));
   }
 
-  const MyClass = function MyClass() {};
+  function MyClass() {}
   Object.defineProperty(MyClass, Symbol.hasInstance, {
     value: function(candidate) {
       return 'mark' in candidate;
     }
   });
 
-  const MySubClass = function MySubClass() {};
+  function MySubClass() {}
   MySubClass.prototype = new MyClass();
 
   let x = new MySubClass();