Add GN isolate support for a bunch of unittests.

tools/gn/BUILD.gn

Index: tools/gn/BUILD.gn
diff --git a/tools/gn/BUILD.gn b/tools/gn/BUILD.gn
index 3109f758bd9c4bb68b8668d22f1863811cb0883f..39fee93ab4014b57400a7eb9a78f48fd16645ea9 100644
--- a/tools/gn/BUILD.gn
+++ b/tools/gn/BUILD.gn
@@ -226,6 +226,15 @@ executable("gn") {
   ]
 }
 
+# TODO(GYP): Delete this after we've converted everything to GN.
+# The _run targets exist only for compatibility w/ GYP.
+group("gn_unittests_run") {
+  testonly = true
+  deps = [
+    ":gn_unittests",
+  ]
+}
+
 test("gn_unittests") {
   sources = [
     "action_target_generator_unittest.cc",
@@ -281,6 +290,11 @@ test("gn_unittests") {
     "value_unittest.cc",
     "visibility_unittest.cc",
   ]
+
+  data = [
+    "format_test_data/",
+  ]
+
   deps = [
     ":gn_lib",
     "//base/test:run_all_unittests",