dillon1000/react

[lower] Bail out on computed lvalues in destructure

--- 

Currently, we're silently producing incorrect output - 

```js 

// source 

function Component(props) { 

const computedKey = props.key; 

const { [computedKey]: x } = props.val; 

return x; 

} 

// compiles to 

function Component(props) { 

const { computedKey: x } = props.val; 

return x; 

} 

```