Simplify //mojo/public/c/system targets

sky/engine/web/BUILD.gn

Index: sky/engine/web/BUILD.gn
diff --git a/sky/engine/web/BUILD.gn b/sky/engine/web/BUILD.gn
index bfd4a353bd99a2ffea2c747f0a55da25d03529bd..0c27709c77109e9609b7eb3d66f294c480241ec8 100644
--- a/sky/engine/web/BUILD.gn
+++ b/sky/engine/web/BUILD.gn
@@ -137,8 +137,8 @@ test("sky_unittests") {
     "//base",
     "//base/test:test_support",
     "//base:i18n",
-    "//sky/engine/wtf:test_support",
     "//sky/engine/testing/platform",
+    "//sky/engine/wtf:test_support",
     "//testing/gmock",
     "//testing/gtest",
     "//third_party/zlib",
@@ -148,6 +148,12 @@ test("sky_unittests") {
     ":web",
   ]
 
+  # TODO(abarth): This is a lie - this test is not embedded in an environment
+  # that injects the system thunks, so system calls don't actually work. This
+  # just tricks the linker into thinking that an implementation of these calls
+  # will be injected at runtime so the link succeeds.
+  deps += [ "//mojo/public/platform/native:system" ]
+
   sources = [
     "tests/RunAllTests.cpp",
   ]