Sketch of on demand snapshot generation for d8

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index e18f2da91d1a03ccdba7e5de40a00c3d86127f71..a30e454b840b1d8e703d98e1820a95cb2ff0da31 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -1565,6 +1565,11 @@ class StartupDataHandler {
     delete[] snapshot_.data;
   }
 
+  void SetSnapshotOnly(const char* snapshot_blob) {
+    Load(snapshot_blob, &snapshot_, v8::V8::SetSnapshotDataBlob);
+  }
+
+
  private:
   void Load(const char* blob_file,
             v8::StartupData* startup_data,
@@ -1619,6 +1624,11 @@ int Shell::Main(int argc, char* argv[]) {
 #endif  // defined(_MSC_VER)
 #endif  // defined(_WIN32) || defined(_WIN64)
   if (!SetOptions(argc, argv)) return 1;
+
+  i::FLAG_harmony_shipping = false;
+  i::FLAG_random_seed = 314159265;
+
+  i::CpuFeatures::Probe(true);
   v8::V8::InitializeICU(options.icu_data_file);
   v8::Platform* platform = v8::platform::CreateDefaultPlatform();
   v8::V8::InitializePlatform(platform);
@@ -1652,7 +1662,12 @@ int Shell::Main(int argc, char* argv[]) {
       base::SysInfo::AmountOfVirtualMemory(),
       base::SysInfo::NumberOfProcessors());
 #endif
+  i::FLAG_logfile_per_isolate = false;
+  create_params.enable_serializer = true;
   Isolate* isolate = Isolate::New(create_params);
+  v8::V8::CreateSnapshotFromHeap(isolate, NULL, NULL, "snapshot.bin", NULL,
+      "snapshot.cc");
+  startup_data.SetSnapshotOnly("snapshot.bin");
   DumbLineEditor dumb_line_editor(isolate);
   {
     Isolate::Scope scope(isolate);