ES31: Remove support of GL_OES_geometry_shader in compiler This patch intends to remove the support of GL_OES_geometry_shader in ANGLE compiler. To make the implementation simpler, currently we decide to only support "GL_EXT_geometry_shader" as the extension string of geometry shader in ANGLE. This patch also updates all the related shaders in angle_unittests into R"()" format. BUG=angleproject:1941 TEST=angle_unittests Change-Id: Ife9858abeedfb46b02c5c2fb1cda16fa27198511 Reviewed-on: https://chromium-review.googlesource.com/773451 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>