Do a GC pass prior to collecting a heap profile.

src/api.cc

 // Copyright 2009 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 3628 matching lines @@
 }
 
 
 void V8::ResumeProfilerEx(int flags, int tag) {
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (flags & PROFILER_MODULE_HEAP_SNAPSHOT) {
     // Snapshot mode: resume modules, perform GC, then pause only
     // those modules which haven't been started prior to making a
     // snapshot.
 
+    // Make a GC prior to taking a snapshot.
+    i::Heap::CollectAllGarbage(false);
     // Reset snapshot flag and CPU module flags.
     flags &= ~(PROFILER_MODULE_HEAP_SNAPSHOT | PROFILER_MODULE_CPU);
     const int current_flags = i::Logger::GetActiveProfilerModules();
     i::Logger::ResumeProfiler(flags, tag);
     i::Heap::CollectAllGarbage(false);
     i::Logger::PauseProfiler(~current_flags & flags, tag);
   } else {
     i::Logger::ResumeProfiler(flags, tag);
   }
 #endif
@@ skipping 581 matching lines @@
 
 
 char* HandleScopeImplementer::Iterate(ObjectVisitor* v, char* storage) {
   HandleScopeImplementer* thread_local =
       reinterpret_cast<HandleScopeImplementer*>(storage);
   thread_local->IterateThis(v);
   return storage + ArchiveSpacePerThread();
 }
 
 } }  // namespace v8::internal