Reapply "[fuchsia] Prepare for setting the Dart target architecture appropriately in the host binar…

utils/application_snapshot.gni

Index: utils/application_snapshot.gni
diff --git a/utils/application_snapshot.gni b/utils/application_snapshot.gni
index 9b5278672c0a1cd7b45b253fa21e723bbc56b852..f2d83193cddd1e7a305d2ddd2085ee090af1f4e6 100644
--- a/utils/application_snapshot.gni
+++ b/utils/application_snapshot.gni
@@ -10,6 +10,9 @@ declare_args() {
   # Default to building app-jit snapshots. The simulator and cross builds
   # override this to script snapshots to cut down on build time.
   dart_snapshot_kind = "app-jit"
+  if (target_cpu != host_cpu) {
+    dart_snapshot_kind = "script"
+  }
 }
 
 template("application_snapshot") {
@@ -25,7 +28,7 @@ template("application_snapshot") {
   if (defined(invoker.deps)) {
     extra_deps += invoker.deps
   }
-  extra_inputs = [main_dart]
+  extra_inputs = [ main_dart ]
   if (defined(invoker.inputs)) {
     extra_inputs += invoker.inputs
   }
@@ -47,16 +50,22 @@ template("application_snapshot") {
     abs_output = rebase_path(output)
     main_file = rebase_path(main_dart)
 
-    args = [ "--packages=$dot_packages",
-             "--snapshot=$abs_output" ]
+    args = [
+      "--packages=$dot_packages",
+      "--snapshot=$abs_output",
+    ]
 
     if (dart_snapshot_kind == "script") {
-      args += ["--snapshot-kind=script",
-               main_file ]
+      args += [
+        "--snapshot-kind=script",
+        main_file,
+      ]
       assert(training_args != "", "Ignoring unused argument")
     } else if (dart_snapshot_kind == "app-jit") {
-      args += ["--snapshot-kind=app-jit",
-               main_file ] + training_args
+      args += [
+                "--snapshot-kind=app-jit",
+                main_file,
+              ] + training_args
     } else {
       assert(false, "Bad dart_snapshot_kind: $dart_snapshot_kind")
     }