[vm/shared] Avoid use of late initialization for vm:shared fields.

Fixes #60687
TEST=tsan

Change-Id: Ibe414f682396f7ffaa19c0f7c902c945ef4c0fab
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/427681
Reviewed-by: Slava Egorov <[email protected]>
Commit-Queue: Alexander Aprelev <[email protected]>

Author: aam

sdk/lib/_internal/vm/lib/ffi_patch.dart

@@ -1924,15 +1924,22 @@ class Native<T> {
   _get_ffi_native_resolver<T extends NativeFunction>();
 
   // Resolver for FFI Native C function pointers.
+  //
+  // TODO(dartbug.com/60699): Once the referenced issue is fixed, this can be
+  // restored back to use of a field with initializer.
   @pragma('vm:entry-point')
   @pragma('vm:shared')
-  static final _ffi_resolver =
-      _get_ffi_native_resolver<
-            NativeFunction<IntPtr Function(Handle, Handle, IntPtr)>
-          >()
-          .asFunction<int Function(Object, Object, int)>();
+  static int Function(Object, Object, int)? _ffi_resolver = null;
 
   @pragma('vm:entry-point')
-  static int _ffi_resolver_function(Object a, Object s, int n) =>
-      _ffi_resolver(a, s, n);
+  static int _ffi_resolver_function(Object a, Object s, int n) {
+    if (_ffi_resolver == null) {
+      _ffi_resolver =
+          _get_ffi_native_resolver<
+                NativeFunction<IntPtr Function(Handle, Handle, IntPtr)>
+              >()
+              .asFunction<int Function(Object, Object, int)>();
+    }
+    return _ffi_resolver!(a, s, n);
+  }
 }