Now, tech companies are betting that users want a new kind of experience: a browser that can answer questions, not just provide a list of links, and that can do far more than just navigate a user to a web page—one that can perform tasks for the user on that page, such as booking travel or completing a purchase. “This is probably the biggest shift since we’ve seen the browser itself become the gateway to the internet. For 30 years, the browser was about navigation. Type, click, explore. Now, with...