This reverts commit 6619c464.

Reason for revert: breaks MEC.

Bug: angleproject:5999

Original change's description:
> FrameCapture: Write the frame cpp file even if frame is empty
>
> The index file will add a reference to this file, and the replay will
> also expect that the frame execution function and the context function
> exist, so write the file even if the frame is empty
>
> Bug: angleproject:5939
> Change-Id: I265d061fdae51b86131d145116ad1c0f9ca8c93f
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2882581
> Commit-Queue: Gert Wollny <gert.wollny@collabora.com>
> Reviewed-by: Cody Northrop <cnorthrop@google.com>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>

Bug: angleproject:5939
Change-Id: I759d44ba847c69faf1caf97a9818836d1be3b058
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2937737Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Commit-Queue: Cody Northrop <cnorthrop@google.com>