* Wrap the return type of indexing getters as Option<T> if necessary.
* Update tests for indexing getters
* Fix typo
* Add comments describing what the code segment is doing
* Update indexing getter usage
* Revert "Add comments describing what the code segment is doing"
This reverts commit 624a14c0fffb78e8eaed21658ddddbad70b2462d.
* Revert "Fix typo"
This reverts commit 487fc307bc08c2a7778b2117fb03f0f5eb5a3c18.
* Revert "Wrap the return type of indexing getters as Option<T> if necessary."
This reverts commit 547f3dd36c1182928ff728a8452591a492b65e21.
* Update the return signatures of WebIDL indexing getters
```
child.push(&JsValue::from(&item.title));
child.push(&JsValue::from(item.completed));
child.push(&JsValue::from(&item.id));
```
Parallel syntax makes it easier to see that each iteration intends to push each of `item`'s fields to `child`.
This commit moves `wasm-bindgen` the CLI tool from internally using
`parity-wasm` for wasm parsing/serialization to instead use `walrus`.
The `walrus` crate is something we've been working on recently with an
aim to replace the usage of `parity-wasm` in `wasm-bindgen` to make the
current CLI tool more maintainable as well as more future-proof.
The `walrus` crate provides a much nicer AST to work with as well as a
structured `Module`, whereas `parity-wasm` provides a very raw interface
to the wasm module which isn't really appropriate for our use case. The
many transformations and tweaks that wasm-bindgen does have a huge
amount of ad-hoc index management to carefully craft a final wasm
binary, but this is all entirely taken care for us with the `walrus`
crate.
Additionally, `wasm-bindgen` will ingest and rewrite the wasm file,
often changing the binary offsets of functions. Eventually with DWARF
debug information we'll need to be sure to preserve the debug
information throughout the transformations that `wasm-bindgen` does
today. This is practically impossible to do with the `parity-wasm`
architecture, but `walrus` was designed from the get-go to solve this
problem transparently in the `walrus` crate itself. (it doesn't today,
but this is planned work)
It is the intention that this does not end up regressing any
`wasm-bindgen` use cases, neither in functionality or in speed. As a
large change and refactoring, however, it's likely that at least
something will arise! We'll want to continue to remain vigilant to any
issues that come up with this commit.
Note that the `gc` crate has been deleted as part of this change, as the
`gc` crate is no longer necessary since `walrus` does it automatically.
Additionally the `gc` crate was one of the main problems with preserving
debug information as it often deletes wasm items!
Finally, this also starts moving crates to the 2018 edition where
necessary since `walrus` requires the 2018 edition, and in general it's
more pleasant to work within the 2018 edition!
