Revert "Build Windows shell (flutter#8331)"

This reverts commit 37534b7.

shell/platform/BUILD.gn

@@ -13,12 +13,9 @@ group("platform") {
     ]
   } else if (is_linux) {
     deps = []
-  } else if (is_win) {
-    deps = [
-      "windows",
-    ]
-  } else if ( is_fuchsia) {
-    # Fuchsia has its own runner implementation.
+  } else if (is_win || is_fuchsia) {
+    # There is no platform target on Windows. Fuchsia has its own runner
+    # implementation.
     deps = []
   } else {
     assert(false, "Unknown/Unsupported platform.")

shell/platform/common/cpp/client_wrapper/publish.gni

@@ -23,10 +23,7 @@ template("publish_client_wrapper") {
   }
 
   copy("${template_target_name}_publish_includes") {
-    visibility = [
-      ":$template_target_name",
-      ":${template_target_name}_publish_sources",
-    ]
+    visibility = [ ":$template_target_name" ]
 
     sources = invoker.public
     outputs = [
@@ -41,12 +38,5 @@ template("publish_client_wrapper") {
     outputs = [
       "$publish_dir_root/{{source_file_part}}",
     ]
-
-    # GN on Windows appears to do #include checks even for copy
-    # targets, so add the dependency to the headers to satisfy
-    # the check.
-    deps = [
-      ":${template_target_name}_publish_includes",
-    ]
   }
 }