Make regress-crbug-514081 less flaky by having max serialization size

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index bedf43ef6671fadc02dec46fd5cce19f549528f6..2b846887c2df687f71be9d07f84e3f089c2a391e 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -304,7 +304,8 @@ class ShellOptions {
         natives_blob(NULL),
         snapshot_blob(NULL),
         trace_enabled(false),
-        trace_config(NULL) {}
+        trace_config(NULL),
+        max_serializer_memory_usage(0) {}
 
   ~ShellOptions() {
     delete[] isolate_sources;
@@ -335,6 +336,7 @@ class ShellOptions {
   const char* snapshot_blob;
   bool trace_enabled;
   const char* trace_config;
+  size_t max_serializer_memory_usage;
 };
 
 class Shell : public i::AllStatic {