GN: Build rules and fixes for (almost) all mojo unittest targets

mojo/public/js/bindings/tests/BUILD.gn

+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# GYP version: mojo/mojo_public_tests.gypi:mojo_js_unittests
+test("mojo_js_unittests") {
+  deps = [
+    "//gin:gin_test",
+    "//mojo/common/test:run_all_unittests",
+    "//mojo/common/test:test_support",
+    "//mojo/environment:chromium",
+    "//mojo/public/interfaces/bindings/tests:test_interfaces",
+    "//mojo/bindings/js",
+  ]
+
+  sources = [ "run_js_tests.cc" ]
+}