Move gn _run target generation into test().

gpu/gles2_conform_support/BUILD.gn

Index: gpu/gles2_conform_support/BUILD.gn
diff --git a/gpu/gles2_conform_support/BUILD.gn b/gpu/gles2_conform_support/BUILD.gn
index de55c13dbb531f0a9c7e8f7ebe302990a3b07b82..29187f0a043943cadf55d03366d0e53f7dfc0a74 100644
--- a/gpu/gles2_conform_support/BUILD.gn
+++ b/gpu/gles2_conform_support/BUILD.gn
@@ -170,15 +170,6 @@ if (internal_gles2_conform_tests) {
   }
 }
 
-# TODO(GYP): Delete this after we've converted everything to GN.
-# The _run targets exist only for compatibility w/ GYP.
-group("gles2_conform_test_run") {
-  testonly = true
-  deps = [
-    ":gles2_conform_test",
-  ]
-}
-
 test("gles2_conform_test") {
   sources = [
     "gles2_conform_test.cc",