Remove compiler_tests.gypi and preprocessor_tests.gypi. These files were a relic of a previous structure, we can safely remove them now that chrome uses angle_unittests.gypi. BUG=None TEST=compiles standalone and with chromium Change-Id: If9a09122f664b740099b4270f5acc5627fc5ac35 Reviewed-on: https://chromium-review.googlesource.com/289343 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>