Check that #version 300 es directive is on the first line ESSL3.00 and 3.10 specs don't allow even newlines before the version directive. BUG=angleproject:1009 TEST=WebGL 2 conformance tests, angle_unittests Change-Id: Id7967829077e35e03572c724e0eafffbed0c975b Reviewed-on: https://chromium-review.googlesource.com/272719 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Zhenyao Mo <zmo@chromium.org>