Disable top level serialization under harmony_scoping. It has broken tests.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 5976cf0794a1a2a308323c715c732c7aec167fe9..06f3dc19d4ec351c7b5b8de84de9ebe639a022d0 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -1243,7 +1243,9 @@ Handle<SharedFunctionInfo> Compiler::CompileScript(
     result = CompileToplevel(&info);
     if (extension == NULL && !result.is_null() && !result->dont_cache()) {
       compilation_cache->PutScript(source, context, result);
-      if (FLAG_serialize_toplevel &&
+      // TODO(dslomov): Issue 3628.
+      // Reenable when harmony scoping serialization issues are fixed.
+      if (FLAG_serialize_toplevel && !FLAG_harmony_scoping &&
           compile_options == ScriptCompiler::kProduceCodeCache) {
         HistogramTimerScope histogram_timer(
             isolate->counters()->compile_serialize());