Move to flutter/lib/snapshot file.

build/archives/BUILD.gn

diff --git a/build/archives/BUILD.gn b/build/archives/BUILD.gn
index 4395228..81f2e53 100644
--- a/build/archives/BUILD.gn
+++ b/build/archives/BUILD.gn
@@ -274,16 +274,3 @@
     ]
   }
 }
-
-if (is_win) {
-  zip_bundle("archive_win_gen_snapshot") {
-    deps = [ "//third_party/dart/runtime/bin:gen_snapshot" ]
-    output = "$target_platform_name-$target_cpu-$flutter_runtime_mode/windows-x64.zip"
-    files = [
-      {
-        source = "$root_out_dir/gen_snapshot.exe"
-        destination = "gen_snapshot.exe"
-      },
-    ]
-  }
-}

lib/snapshot/BUILD.gn

diff --git a/lib/snapshot/BUILD.gn b/lib/snapshot/BUILD.gn
index 618640e..e29a129 100644
--- a/lib/snapshot/BUILD.gn
+++ b/lib/snapshot/BUILD.gn
@@ -290,3 +290,16 @@
 group("kernel_platform_files") {
   public_deps = [ ":strong_platform" ]
 }
+
+if (is_win) {
+  zip_bundle("archive_win_gen_snapshot") {
+    deps = [ "//third_party/dart/runtime/bin:gen_snapshot" ]
+    output = "$target_platform_name-$target_cpu-$flutter_runtime_mode/windows-x64.zip"
+    files = [
+      {
+        source = "$root_out_dir/gen_snapshot.exe"
+        destination = "gen_snapshot.exe"
+      },
+    ]
+  }
+}