Generate flow types from recent style-spec changes

[lbud]

As pointed out in #5449 (comment), that PR failed to remove the contextType parameter from the CanvasSourceSpecification flow type. I ran the build script to generate it and it looks like our type definitions are out of date for a few things. @jfirebaugh or @anandthakker — is it weird that flow testing on local machines/CI hasn't complained about these? 🤔

[anandthakker]

is it weird that flow testing on local machines/CI hasn't complained about these?

Good question. I think the reasons there were no complaints is that we're never explicitly calling new CanvasSource(...) except in a unit test (see also #5373) -- so there was no file that flow was checking where we actually omitted the contextType property.