Disallow calling DSLWriter::Var more than once.

Previously, DSLVars would keep track of their `fInitialized`
state, and calling Var twice would just return the already-
initialized values. However, the only remaining use case of
calling Var() a second time was in `Parser::addToSymbolTable`.
Now the only caller of `Var` is `Declaration`, and it isn't
called more than once.

This allows us to remove the `fInitialized` flag.

Change-Id: Ibf5a4797aff72bebdd58a85ed8816eb87ecba650
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/699596
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed