dillon1000/react

InferReactivePlaces accounts for mutable aliasing

Fixes T175227223. When inferring reactivity, mutation of a value with a reactive 
input marks the mutable value as reactive. However, we also need to account for 
aliases: 

```javascript 

const x = []; 

const y = x; 

y.push(props.value); 

``` 

Previously we would have only considered `y` reactive here, but `x` also becomes 
reactive. 

The implementation extracts out a helper from InferReactiveScopeVariables that 
builds a `DisjointSet<Identifier>` of disjoint sets of mutably aliased values. 
InferReactivePlaces then treats all instances of each mutable alias group as 
equivalent for reactivity purposes.