Use conservative hash table capacity growth during entire snapshotting.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 125a31be06f94b802e9f61a465335ee641b8c189..c7126d742c4628b45ab064e3cbb3756c7ca87120 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -347,12 +347,14 @@ StartupData V8::CreateSnapshotDataBlob(const char* custom_source) {
     base::ElapsedTimer timer;
     timer.Start();
     Isolate::Scope isolate_scope(isolate);
+    internal_isolate->set_creating_default_snapshot(true);
     internal_isolate->Init(NULL);
     Persistent<Context> context;
     i::Snapshot::Metadata metadata;
     {
       HandleScope handle_scope(isolate);
       Handle<Context> new_context = Context::New(isolate);
+      internal_isolate->set_creating_default_snapshot(false);
       context.Reset(isolate, new_context);
       if (custom_source != NULL) {
         metadata.set_embeds_script(true);