This will eventually replace the existing annoteded_decl for cursor
info, and be added to doc info as well. For now put in under a
different field name to not break existing clients.
For now, just reimplement the existing annotations but put in tag names
that are specific to the kind of type/decl. The goal is to fill in a
lot more substructure/detail over time.
Incidentally flesh out some cursor info tests.
rdar://problem/24292226
There's a group of methods in `DeclContext` with names that start with *is*,
such as `isClassOrClassExtensionContext()`. These names suggests a boolean
return value, while the methods actually return a type declaration. This
patch replaces the *is* prefix with *getAs* to better reflect their interface.
The code goes into its own sub-tree under 'tools' but tests go under 'test',
so that running 'check-swift' will also run all the SourceKit tests.
SourceKit is disabled on non-darwin platforms.
