Constructor.
The "fallback" strategy when ESI is not available should always be an instance of InlineFragmentRenderer.
InlineFragmentRenderer $inlineStrategy The inline strategy to use when ESI is not supported:
public function __construct(Esi $esi, InlineFragmentRenderer $inlineStrategy) {
$this->esi = $esi;
$this->inlineStrategy = $inlineStrategy;
}