NEW YORK — The 1990s was a heady decade: the Internet became available to the public, Nelson Mandela was elected president of South Africa, Prince Charles and Princess Diana divorced and several nations joined forces to wage war in the Persian Gulf. In the realm of pop culture, Nirvana conquered the music charts with their anthem Smells Like Teen Spirit, Friends debuted on TV, and the first Harry Potter book was published. Like every decade, the 1990s had its share of now-iconic toys, which ’90s kids — now adults — want to buy back. And that’s why 1990s toys are hot now.