TextDecoder defaults to stream: true instead of false with null options

[ChALkeR]

> new TextDecoder('utf-16le').decode(Uint8Array.of(0x80), null)
''

For any multi-byte encoding except utf-8 fast path

Should be:

> new TextDecoder('utf-16le').decode(Uint8Array.of(0x80), null)
'�'

This code here is wrong:

node/lib/internal/encoding.js

Lines 475 to 477 in 8365edc

	let flags = 0;
	if (options !== null)
	flags |= options.stream ? 0 : CONVERTER_FLAGS_FLUSH;

When options is null (instead of default empty object), flags is 0, but should be CONVERTER_FLAGS_FLUSH

Overall, the flags-based logic is too complex and convoluted

Will be fixed in #61409