[compiler][ez] Only fail gating hoisting check for referenced identifiers

Reduce false positive bailouts by using the same `isReferencedIdentifier` logic that the compiler also uses for determining context variables and a function's own hoisted declarations.

Details:
Previously, we counted every babel identifier as a reference. This is
problematic because babel counts most string symbols as an identifier.

```js
print(x);  // x is an identifier as expected
obj.x      // x is.. also an identifier here
{x: 2}     // x is also an identifier here
```

This PR adds a check for `isReferencedIdentifier`. Note that only non-lval
references pass this check. This should be fine as we don't need to hoist function declarations before writes to the same lvalue (which should error in strict mode anyways)
```js
print(x);  // isReferencedIdentifier(x) -> true
obj.x      // isReferencedIdentifier(x) -> false
{x: 2}     // isReferencedIdentifier(x) -> false
x = 2      // isReferencedIdentifier(x) -> false
```