Teach PRESUBMIT.py how to run gn check for most of the mojo repo

mojo/cc/BUILD.gn

Index: mojo/cc/BUILD.gn
diff --git a/mojo/cc/BUILD.gn b/mojo/cc/BUILD.gn
index 1a78c01090026fa4b9b3d6c3bd68aaf52f0966d5..6fb9a1487f1801441d42bdafda84dd97885be136 100644
--- a/mojo/cc/BUILD.gn
+++ b/mojo/cc/BUILD.gn
@@ -8,11 +8,14 @@ source_set("cc") {
     "//base",
     "//cc",
     "//cc/surfaces",
-    "//skia",
     "//gpu/command_buffer/client:gles2_implementation",
+    "//gpu/command_buffer/client:gles2_interface",
     "//mojo/converters/surfaces",
+    "//mojo/public/cpp/environment",
+    "//mojo/public/cpp/system",
     "//mojo/public/gles2:for_shared_library",
     "//mojo/services/public/interfaces/surfaces",
+    "//skia",
   ]
 
   sources = [