* Removed unnecessary 'return' statements.
Returning a 'Promise' value in 'promise.then()' makes promise chains.
Used memory and promises are not garbage collected
until finishing 'helpers.asyncToGenerator'.
* Update test
* formatting
* fix `typeof Symbol.prototype`
Babel uses a helper function to return the correct value for `typeof
obj` when obj is a Symbol and support for Symbol has been polyfilled.
This function assumes that `obj.constructor === Symbol` implies `typeof
obj === 'symbol'`.
This isn't true when obj is `Symbol.prototype`. In that case (REPL from
node 6, the same holds in Firefox):
```
> Symbol.prototype.constructor === Symbol
true
> typeof Symbol.prototype
'object'
>
```
AFAICS, that's the only case where the assumption doesn't hold.
The test added by this patch fails only on node 0.10, as 0.12 already
has a native implementation of Symbol and the polyfill code doesn't run.
This caused a problem in core-js when it's compiled with babel (the
issue was isolated by @skozin here:
https://github.com/zloirock/core-js/issues/189#issuecomment-209864582).
- Have the `jsx` helper do the `defaultProps` work instead of calling `defaultProps` inline.
- Put `key` after `props` and make it optional.
- Inline `children` as rest args instead of in the object.
- Rename `createRawReactElement` to `jsx`. I wish I was kidding.
Most of these are silly microoptimizations. In my test file (based off an internal RN app), this reduces the parsing overhead of inlining from around 1% to 0.1% in JSC and from 0.6% to 0.0% in V8 (compared to element inlining before this commit).
Once parsed, the initial render with inlining is the same speed as not inlining in JSC and ~1% slower in V8. A second initial render in the same context (reusing the function objects, JIT, etc) is 2.0% faster in JSC and 5.5% faster in V8.
Either due to lower parsing costs or better type inference, this seems
to perform better than direct object inlining. (All along, the main win
was skipping a loop through props, not avoiding a function call.)
