[Development] Qt for WebAssembly feature freeze exceptions

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Hi all, 

We have two pending changes for the wasm platform which I'd like to request a feature freeze exception for:

	* Adding the initial accessibility backend. This feature will initially be opt-in, and we are
	  aiming to make it as non-disruptive as possible. A couple of details remains to be settled
	 on the review.

	* Updating the SDK to the latest Emcscripten version

(It’s a bit unclear which freeze policy (if any) applies to the SDK update. In any case it needs to be done.)

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