Vulkan: Warm up glslang on startup As soon as glslang is initialized (which is done when EGL is initialized), try to compile a simple shader. This will warm up glslang's internals to avoid hitches on first shader compilation when a WebGL application starts. Potential future optimization is to use a worker thread to do this. Bug: chromium:1091440 Change-Id: I6ac22e982d748af52a6e8b61239889425edc2edb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2280401 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>