The data structure was originally added in
41e1cd185b82a518c58c92544c45f0348c03ef74 and then removed in
50a336fff899ebd8a687c453ec6beb18a5a9baf9, but brought back in
711bf55eaa643c3d05640bebbf3e4315477b8ed8 for Decl in the compiler
frontend, and then the last reference to it was eliminated in
548a087fafeda5b07d2237d5137906b8d07da699 which removed Decl in favor of
Nav and Cau.
Also remove `@frameSize`, closing #3654.
While the other machinery might remain depending on #23446, it is
settled that there will not be `async`/ `await` keywords in the
language.
The compiler actually doesn't need any functional changes for this: Sema
does reification based on the tag indices of `std.builtin.Type` already!
So, no zig1.wasm update is necessary.
This change is necessary to disallow name clashes between fields and
decls on a type, which is a prerequisite of #9938.
This reverts commit 0c99ba1eab63865592bb084feb271cd4e4b0357e, reversing
changes made to 5f92b070bf284f1493b1b5d433dd3adde2f46727.
This caused a CI failure when it landed in master branch due to a
128-bit `@byteSwap` in std.mem.
