Add isNaN helper for IE11

[andrewiggins]

According to our Saucelabs tests, IE11 doesn't support Number.isNaN so I've added a littler helper to use instead.

Also fixed some quotes in one of our npm scripts so it works correctly on Windows

[github-actions]

Size Change: +1 B

Total Size: 56.6 kB

Filename	Size	Change
debug/dist/debug.module.js	3.52 kB	+1 B

ℹ️ View Unchanged

Filename	Size	Change
compat/dist/compat.js	4.07 kB	0 B
compat/dist/compat.module.js	4 kB	0 B
compat/dist/compat.umd.js	4.13 kB	0 B
debug/dist/debug.js	3.53 kB	0 B
debug/dist/debug.umd.js	3.6 kB	0 B
devtools/dist/devtools.js	232 B	0 B
devtools/dist/devtools.module.js	240 B	0 B
devtools/dist/devtools.umd.js	315 B	0 B
dist/preact.js	4.25 kB	0 B
dist/preact.min.js	4.28 kB	0 B
dist/preact.min.module.js	4.28 kB	0 B
dist/preact.min.umd.js	4.31 kB	0 B
dist/preact.module.js	4.28 kB	0 B
dist/preact.umd.js	4.32 kB	0 B
hooks/dist/hooks.js	1.53 kB	0 B
hooks/dist/hooks.module.js	1.56 kB	0 B
hooks/dist/hooks.umd.js	1.61 kB	0 B
jsx-runtime/dist/jsxRuntime.js	360 B	0 B
jsx-runtime/dist/jsxRuntime.module.js	326 B	0 B
jsx-runtime/dist/jsxRuntime.umd.js	441 B	0 B
test-utils/dist/testUtils.js	442 B	0 B
test-utils/dist/testUtils.module.js	444 B	0 B
test-utils/dist/testUtils.umd.js	526 B	0 B

_{compressed-size-action}

[github-actions]

Coverage: 99.706%. Remained the same when pulling 70e3e76 on fix-ie11-tests into 7adb147 on master.