Better threaded fuzzing for TestFunctionCallOptimization

R=verwaest@chromium.org

BUG=

Review URL: https://codereview.chromium.org/182863002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19567 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/cctest/test-api.cc

@@ -21925,6 +21925,7 @@ class ApiCallOptimizationChecker {
 
   static void OptimizationCallback(
       const v8::FunctionCallbackInfo<v8::Value>& info) {
+    ApiTestFuzzer::Fuzz();
     CHECK(callee == info.Callee());
     CHECK(data == info.Data());
     CHECK(receiver == info.This());