dillon1000/react

[RFC] useEffect dependency memoization check

This is one approach to testing whether useEffect dependencies are memoized. The 
idea is based off the observation that the only reason dependencies wouldn't be 
memoized (other than compiler bugs) is that they are mutated later. If they're 
mutated later, then the dep array will have a mutable range which encompasses 
the InstructionId of the useEffect call. So we look for that pattern and throw a 
validation error. 

The downside of this approach is that we might reject code that happens to be 
valid: specifically, that the lack of memoization isn't a problem in practice 
because the effect won't trigger a loop. But (per test plan) this doesn't seem 
to introduce that many new bailouts on www. Rather than implement a complex 
validation that checks whether we un-memoized something that was memoized in the 
input, it seems more practical to: 

1. Enable this more comprehensive validation against any form of un-memo'd 
effect dependency 

2. Flip the default for hooks (to assume they follow the rules), which will fix 
the primary cause of Forget pessimistically not memoizing dependencies. 

## Test Plan 

Synced to www and checked output via the upgrade script: a few components stop 
getting memoized bc they have un-memoized effect dependencies. Let's chat!