Tests: Add reduced crashing shader test Reduced case of a shader that crashes an app during SPIR-V compile. Test: GLSLTest_ES3.NestedPowFromUniform Bug: b/217922015 Change-Id: I8d0ccd8b2c4f4e8e51ac39c9dbfaafbf48423157 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3965051 Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Cody Northrop <cnorthrop@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>