test: make use of Number.isNaN to test-readfloat.js

PR-URL: #17310
Reviewed-By: Yosuke Furukawa <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Daijiro Wachi <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Jon Moss <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: hiromoon

test/parallel/test-readfloat.js

@@ -29,7 +29,7 @@ function test(clazz) {
   buffer[1] = 0xff;
   buffer[2] = 0x7f;
   buffer[3] = 0x7f;
-  assert.ok(isNaN(buffer.readFloatBE(0)));
+  assert.ok(Number.isNaN(buffer.readFloatBE(0)));
   assert.strictEqual(3.4028234663852886e+38, buffer.readFloatLE(0));
 
   buffer[0] = 0xab;