No reference when awaiting custom GetAwaiter method

[HaloFour]

Version Used: v15.6.4

Steps to Reproduce:

1. Create a class with a custom GetAwaiter that returns an awaitable.
2. Instantiate that class and await on it from a separate async method.

Expected Behavior:

That the GetAwaiter method shows references from being used in an await expression.

Actual Behavior:

[HaloFour]

Whether or not the method is shown as having a reference is a bit inconsistent between features. For example, GetEnumerator and Deconstruct do reflect the reference if used with foreach or deconstruction respectively. But LINQ-compatible methods don't appear to reflect the reference if used from LINQ query syntax.

[jcouv]

Fix will ship in 15.8.Preview5.