dillon1000/react

[patch][babel] check babel identifier before lowering to HoistedConst

Same babel identifier issue as #2510 but for HoistedConst 

Not sure how we should best test this -- one possibility is using constant prop. 
Currently, we have false positives for HoistedConst that prevent constant 
propagation. I don't want to over-rotate on babel apis tests in our fixtures 
(instead of semantically interesting ones) 

```js 

// input 

function Component() { 

{ x: 4 }; 

const x = 2; 

return x; 

} 

// output 

function Component() { 

const $ = useMemoCache(1); 

let x; 

if ($[0] === Symbol.for("react.memo_cache_sentinel")) { 

x = 2; 

$[0] = x; 

} else { 

x = $[0]; 

} 

return x; 

} 

```