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

ui/compositor/BUILD.gn

Index: ui/compositor/BUILD.gn
diff --git a/ui/compositor/BUILD.gn b/ui/compositor/BUILD.gn
index 283d1ab8a6c2b4f111f19ffde643d410a3a5d422..498a505a334bef66ea39fc8cd58ac5ee38c2e874 100644
--- a/ui/compositor/BUILD.gn
+++ b/ui/compositor/BUILD.gn
@@ -134,13 +134,16 @@ source_set("test_support") {
     "//gpu/skia_bindings",
     "//skia",
     "//testing/gtest",
-    "//third_party/WebKit/public:blink_minimal",

[danakj, 2015/07/22 18:25:27]

This looks historical. Do we actually need this still?

[Dirk Pranke, 2015/07/22 18:49:36]

You're suggesting maybe we never need blink headers in the compositor, even on
desktop platforms?

[danakj, 2015/07/22 19:03:14]

I don't see any includes of third_party/WebKit in ui/compositor, nor is it
allowed in DEPS anymore.

[sdefresne, 2015/07/23 07:38:03]

Done.

     "//ui/base",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
   ]
 
+  if (!is_ios) {
+    deps += [ "//third_party/WebKit/public:blink_minimal" ]
+  }
+
   if (use_x11) {
     configs += [ "//build/config/linux:x11" ]
     deps += [ "//ui/gfx/x" ]