GN: Make wtf_unittests build on mac/clang

Source/wtf/BUILD.gn

Index: Source/wtf/BUILD.gn
diff --git a/Source/wtf/BUILD.gn b/Source/wtf/BUILD.gn
index f418699e77fd9ee34084f9e66e0dee81f22a4b34..83dde4c3aab4a87f84817000cea4ac97de8fcd48 100644
--- a/Source/wtf/BUILD.gn
+++ b/Source/wtf/BUILD.gn
@@ -41,11 +41,15 @@ config("wtf_config") {
 component("wtf") {
   sources = gypi_values.wtf_files
 
+  configs += [
+    "//third_party/WebKit/Source:config",
+    "//third_party/WebKit/Source:non_test_config",
+  ]
+
   defines = [ "WTF_IMPLEMENTATION=1" ]
 
   direct_dependent_configs = [
     ":wtf_config",
-    "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:features",
   ]
 
@@ -98,6 +102,8 @@ test("wtf_unittests") {
     ]
   }
 
+  configs += [ "//third_party/WebKit/Source:config", ]
+
   deps = [
     ":run_all_tests",
     ":unittest_helpers",
@@ -117,6 +123,7 @@ source_set("run_all_tests") {
   configs += [
     ":wtf_config",
     "//third_party/WebKit/Source:config",
+    "//third_party/WebKit/Source:non_test_config",
   ]
 
   deps = [
@@ -130,6 +137,12 @@ component("unittest_helpers") {
   sources = gypi_values.wtf_unittest_helper_files
   defines = [ "WTF_UNITTEST_HELPERS_IMPLEMENTATION=1" ]
 
+  configs += [
+    ":wtf_config",
+    "//third_party/WebKit/Source:config",
+    "//third_party/WebKit/Source:non_test_config",
+  ]
+
   deps = [
     ":wtf",
   ]