getContext does not work through {#await}

[spiffytech]

Describe the bug
Attempting to getContext in a component that's rendered inside an {#await} block returns undefined, instead of the context value.

To Reproduce
https://svelte.dev/repl/018e3f0afffd41edb87b6c3dc5b38d62?version=3.6.10

Expected behavior
I expect getContext to always return the context value, regardless of how the component gets rendered.

Information about your Svelte project:

• Your browser and the version: Chrome 75, Firefox

• Your operating system: Chrome OS

• Svelte version: Svelte 3.6.7, 3.6.10

• Webpack, REPL

Severity
I'm trying to pass stores around. Luckily, I can import the stores directly, but since my whole app is rendered inside an {#await} block, this probably blocks all of setContext/getContext for me until it's fixed or I find a workaround.

[Conduitry]

Duplicate of #2443.