Revert "Change kernel platform generation dependency name (#4189)" (#4192)

This reverts commit 83224fb6.

BUILD.gn

@@ -6,7 +6,7 @@ group("flutter") {
   testonly = true
 
   deps = [
-    "//flutter/lib/snapshot:compile_platform",
+    "//flutter/lib/snapshot:flutter_patched_sdk",
     "//flutter/lib/snapshot:generate_snapshot_bin",
     "//flutter/sky",
     "//flutter/third_party/txt",

lib/snapshot/BUILD.gn

@@ -413,8 +413,7 @@ action("compile_platform") {
 
   args = [
             "--target=flutter",
-            "dart:core",
-            "dart:vmservice_sky",
+            "dart:core"
          ] + rebase_path(sources, root_build_dir) +
          rebase_path(outputs, root_build_dir)
 }