Expose gc(true) to JavaScript, which triggers a scavenger GC.

src/extensions/gc-extension.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 22 matching lines @@
 const char* const GCExtension::kSource = "native function gc();";
 
 
 v8::Handle<v8::FunctionTemplate> GCExtension::GetNativeFunction(
     v8::Handle<v8::String> str) {
   return v8::FunctionTemplate::New(GCExtension::GC);
 }
 
 
 v8::Handle<v8::Value> GCExtension::GC(const v8::Arguments& args) {
-  HEAP->CollectAllGarbage(Heap::kNoGCFlags, "gc extension");
+  if (args[0]->BooleanValue()) {
+    HEAP->CollectGarbage(NEW_SPACE, "gc extension");
+  } else {
+    HEAP->CollectAllGarbage(Heap::kNoGCFlags, "gc extension");
+  }
   return v8::Undefined();
 }
 
 
 void GCExtension::Register() {
   static GCExtension gc_extension;
   static v8::DeclareExtension declaration(&gc_extension);
 }
 
 } }  // namespace v8::internal