test: fix isNAN->Number.isNAN

PR-URL: #17309
Reviewed-By: Yosuke Furukawa <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Daijiro Wachi <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Jon Moss <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: ykyz

test/parallel/test-writedouble.js

@@ -168,8 +168,8 @@ function test(clazz) {
   // Darwin ia32 does the other kind of NaN.
   // Compiler bug.  No one really cares.
   assert(0x7F === buffer[15] || 0xFF === buffer[15]);
-  assert.ok(isNaN(buffer.readDoubleBE(0)));
-  assert.ok(isNaN(buffer.readDoubleLE(8)));
+  assert.ok(Number.isNaN(buffer.readDoubleBE(0)));
+  assert.ok(Number.isNaN(buffer.readDoubleLE(8)));
 }