Put back ConfigureBundle. (flutter/engine#4219)

It was accidently removed in 948a60c83d.

engine/src/flutter/shell/common/engine.cc

@@ -241,6 +241,7 @@ void Engine::RunBundleAndSource(const std::string& bundle_path,
 
   std::vector<uint8_t> platform_kernel;
   if (!bundle_path.empty()) {
+    ConfigureAssetBundle(bundle_path);
     GetAssetAsBuffer(blink::kPlatformKernelAssetKey, &platform_kernel);
   }
   ConfigureRuntime(GetScriptUriFromPath(bundle_path), platform_kernel);