Fix some gn_visibility TODOs.

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 453 matching lines @@
       "//sync/tools:sync_client",
       "//sync/tools:sync_listen_notifications",
       "//testing/gmock:gmock_main",
       "//third_party/mojo/src/mojo/edk/test:mojo_public_system_perftests",
       "//tools/perf/clear_system_cache",
       "//ui/keyboard:keyboard_unittests",
       "//ui/message_center:message_center_unittests",
       "//ui/snapshot:snapshot_unittests",
       "//ui/views/examples:views_examples_with_content_exe",
 
-      # "//v8:v8_snapshot",  # TODO(GYP): visibility?
-      # "//v8:postmortem-metadata",  # TODO(GYP): visibility?
-
       "//third_party/codesighs:nm2tsv",
       "//third_party/sqlite:sqlite_shell",
     ]
 
     if (current_toolchain == host_toolchain) {
       # Do not build the breakpad utilities in cross-compiles.
       deps += [
         "//breakpad:dump_syms",
         "//breakpad:microdump_stackwalk",
         "//breakpad:minidump_dump",
@@ skipping 248 matching lines @@
 
 group("gn_visibility") {
   deps = [
     "//build/config/sanitizers:options_sources",
 
     # "//third_party/pdfium:pdfium_embeddertests",  # TODO(GYP): visibility?
     # "//third_party/pdfium:pdfium_unittests",  # TODO(GYP): visibility?
 
     "//ui/resources:repack_ui_test_mac_locale_pack",
 
-    # "//v8:v8_snapshot",  # TODO(GYP): visibility?
-    # "//v8:postmortem-metadata",  # TODO(GYP): visibility?
+    "//v8:v8_snapshot",
+    "//v8:postmortem-metadata",
   ]
 }
 
 if (!is_ios) {
   # This group includes all of the targets needed to build and test Blink,
   # including running the layout tests (see below).
   group("blink_tests") {
     testonly = true
 
     deps = [
@@ skipping 175 matching lines @@
       "//ui/views:views_unittests",  # TooltipControllerTest failures
       "//ui/wm:wm_unittests",  # PASSES 4/21/2015
       "//url:url_unittests",  # PASSES 4/17/2015
 
       # TODO(GYP) nacl_integration
       # TODO(GYP) telemetry_perf_unittests
       # TODO(GYP) telemetry_unittests
     ]
   }
 }