[Fuchsia] Disable cast_shell

cast_shell is not useful on Fuchsia. Removed the cast_shell_fuchsia
target and turned off cast_shell, cast_shell_browsertests and
cast_shell_unittests in gn_all.

Bug: 893229
Change-Id: I12a76f1bfdde657bd1d1d5a9ebfa73dcde445127
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1960889
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Auto-Submit: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#725740}

diff --git a/BUILD.gn b/BUILD.gn
index 6e6e8a8..b309339 100644
--- a/BUILD.gn
+++ b/BUILD.gn

@@ -650,7 +650,11 @@
   }
 
   if (is_chromecast) {
-    deps += [ "//chromecast:cast_shell" ]
+    deps += [ "//chromecast:cast_test_lists" ]
+
+    if (!is_fuchsia) {
+      deps += [ "//chromecast:cast_shell" ]
+    }
     if (enable_extensions && use_aura) {
       deps += [ "//chrome/browser/resources/chromeos/accessibility/chromevox" ]
     }