Vulkan: Add IMAGE_USE_STORAGE bit only if necessary.
Vulkan: Add IMAGE_USE_STORAGE bit only if necessary.

The VK_IMAGE_USAGE_STORAGE_BIT has negative performance impact. Right
now we needed for overlay widgets. This CL will only add the bit if we
actually have widget enabled.

Bug: b/157774833
Change-Id: I3027df886c9b34ccfd667152fa4fb090dfadb45b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2225810
Reviewed-by: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Commit-Queue: Charlie Lao <2661ca4ca24c371418789adbc76dfb4875087223@google.com>

ppy/angle,ppy/angle,ppy/angle,ppy/angle