Fix running gn gen for //ui/* targets on iOS.

ui/gfx/BUILD.gn

Index: ui/gfx/BUILD.gn
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index c14d22d4af7dfc863403da7745d5c04b5388bb73..000f31945dc4219fac5ba99d4e33f0a2019253ea 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -508,7 +508,6 @@ test("gfx_unittests") {
       "range/range_mac_unittest.mm",
       "range/range_unittest.cc",
       "range/range_win_unittest.cc",
-      "render_text_unittest.cc",
       "sequential_id_generator_unittest.cc",
       "shadow_value_unittest.cc",
       "skbitmap_operations_unittest.cc",
@@ -518,6 +517,10 @@ test("gfx_unittests") {
     ]
   }
 
+  if (!is_android && !is_ios) {
+    sources += [ "render_text_unittest.cc" ]
+  }
+
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
@@ -551,13 +554,9 @@ test("gfx_unittests") {
     ]
   }
 
-  if (is_android || is_ios) {
-    sources -= [ "render_text_unittest.cc" ]
-  }
-
   if (use_aura) {
     sources -= [ "screen_unittest.cc" ]
-  } else {
+  } else if (!is_ios) {
     sources -= [ "nine_image_painter_unittest.cc" ]
   }