[fuchsia] Fix failing build.

Author: akbiggs

shell/platform/fuchsia/flutter/software_surface.cc

@@ -6,6 +6,7 @@
 
 #include <lib/async/default.h>
 #include <lib/ui/scenic/cpp/commands.h>
+#include <lib/zx/cpp/fidl.h>
 #include <zircon/status.h>
 #include <zircon/types.h>
 
@@ -19,6 +20,7 @@
 #include "third_party/skia/include/core/SkImageInfo.h"
 
 #include "../runtime/dart/utils/inlines.h"
+#include "zx/cpp/fidl.h"
 
 namespace flutter_runner {