+ Small refactoring in SimpleOperationTest.cpp to share
the vertex/fragment shaders for all the tests.
+ Adjust deqp gles2 expectations to include
dEQP-GLES2.functional.draw.draw_arrays.lines.single_attribute

Bug: angleproject:2328

Change-Id: I7cab84b7914f503537eb5bfabb7ed58002e19846
Reviewed-on: https://chromium-review.googlesource.com/899046
Commit-Queue: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>