1. refine the check for "origin_upper_left" and "pixel_center_integer"

2. gl_FragCoord can be used at ogl140 with extension "GL_ARB_fragment_coord_conventions".




Signed-off-by: ZhiqianXia <xzq0528@outlook.com>

gtests/AST.FromFile.cpp

@@ -294,6 +294,7 @@ INSTANTIATE_TEST_SUITE_P(
         "BestMatchFunction.vert",
         "EndStreamPrimitive.geom",
         "floatBitsToInt.vert",
+        "coord_conventions.frag",
     })),
     FileNameAsCustomTestSuffix
 );