Compile webui_closure_compile target on all desktop platforms.

This CL adds the webui_closure_compile target to all desktop platforms.
It was previously only run on platforms where "all" was the target but
some bots such as linux-chromeos-rel used "gn_all".

Bug: 632206
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: If4d000ab1e9d8c2b0fe999c614277a6a1e4a95e8
Reviewed-on: https://chromium-review.googlesource.com/852604
Commit-Queue: calamity <calamity@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531156}

BUILD.gn

@@ -91,6 +91,7 @@ group("gn_all") {
 
   if (!is_ios && !is_android && !is_chromecast && !is_fuchsia) {
     deps += [
+      ":webui_closure_compile",
       "//chrome",
       "//chrome/installer/zucchini:zucchini",
       "//chrome/installer/zucchini:zucchini_unittests",
@@ -1149,13 +1150,10 @@ template("assert_valid_out_dir") {
       "Do not use a platform name in your output directory (found \"$root_build_dir\"). http://crbug.com/548283")
 }
 
-if (!is_win || !is_clang) {
-  group("webui_closure_compile") {
-    data_deps = []
-    if (is_chromeos) {
-      data_deps +=
-          [ "//chrome/browser/resources/chromeos/login:closure_compile" ]
-    }
+group("webui_closure_compile") {
+  data_deps = []
+  if (is_chromeos) {
+    data_deps += [ "//chrome/browser/resources/chromeos/login:closure_compile" ]
   }
 }