It’s been a rollercoaster for Bruce Ratner’s plan to build a giant sports arena on a mostly derelict sliver of land in Brooklyn: First, it was, “Frank Gehry’s gonna design it!” And then the funding became shaking, because of the recession. Gehry’s plan was scaled back, then scrapped. Looked dead. But SHoP came aboard, for a faster, cheaper design! Then…silence. Finally, there’s light: Ratner has secured the sale of $511 million in tax-exempt bonds to fund the construction. And quick as a wink, the traffic detours are going up, and the construction is set to begin any day now.