HLSL: Insert return statements into functions that are missing them. It's allowed to not have all code paths return a value in ESSL but the HLSL compiler detects this and generates an error. Work around this by adding dummy return statements at the end of each function that doesn't have one. TEST=deqp/data/gles2/shaders/functions.html BUG=angleproject:1015 BUG=478572 Change-Id: I2913f90f0994d4caf25cc43b16b9fc4e9efb19a5 Reviewed-on: https://chromium-review.googlesource.com/362085 Reviewed-by: Zhenyao Mo <zmo@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>