Enables GN build on windows

runtime/vm/BUILD.gn

 # Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 config("libdart_vm_config") {
-  # TODO(zra, jamesr): This check can go away after some problems with the
-  # fuchsia toolchain definition are fixed.
-  if (!defined(is_fuchsia) || !is_fuchsia) {
-    libs = [ "dl" ]
-
-    if (!is_android) {
-      libs += [ "pthread" ]
-
-      if (is_linux) {
-        libs += [ "rt" ]
-      }
-    }
-  } else {
+  if (defined(is_fuchsia) && is_fuchsia) {
     libs = [
       "magenta",
       "runtime",
     ]
+  } else if (is_win) {
+    libs = [
+      "advapi32.lib",
+      "shell32.lib",
+      "dbghelp.lib",
+    ]
+  } else {
+    libs = [ "dl" ]
+    if (!is_android) {
+      libs += [ "pthread"]
+    }
+    if (is_linux) {
+      libs += [ "rt" ]
+    }
   }
 }
 
 
 static_library("libdart_platform") {
   configs += ["..:dart_config",
               "..:dart_maybe_product_config"]
   public_configs = [":libdart_vm_config"]
 
   platform_headers_gypi =
@@ skipping 258 matching lines @@
     ["developer", "developer", true, "../../sdk/lib/developer", "../lib"],
     ["_internal", "internal", true, "../../sdk/lib/internal", "../lib"],
     ["isolate", "isolate", true, "../../sdk/lib/isolate", "../lib"],
     ["math", "math", true, "../../sdk/lib/math", "../lib"],
     ["mirrors", "mirrors", true, "../../sdk/lib/mirrors", "../lib"],
     ["profiler", "profiler", false, "../../sdk/lib/profiler"],
     ["typed_data", "typed_data", false, "../lib"],
     ["_vmservice", "vmservice", true, "../../sdk/lib/vmservice", "../lib"],
   ]
 }