dillon1000/react

Use single name resolver for nested functions

This is a prerequisite to inlining `useMemo()` lambdas so that we can better 
optimize them. Nested functions are evaluated with a fresh HIRBuilder, which 
means that they currently have their own `bindings` object for mapping 
identifier instances to IdentifierIds. This means that identifier ids in a 
closure are _always_ different that those outside the closure, even when they 
refer to the same identifier: 

``` 

function Component(props) { 

props; // becomes e.g. props$1 

const onClick = () => { 

props // becomes e.g. props$2 

}; 

} 

``` 

For useMemo inlining this is problematic because we've lost the association that 
these identifiers actually refer to the same thing. This PR changes that, 
sharing the name resolution data structure between the top-level function and 
any nested function expressions.