[builtins] Add --print-builtin-size flag

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index faa04848cff43c13c49ff5837ecb6718deac3822..4e6ad8524d72a72eefb103d7c06ba0d4323cbe09 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2660,6 +2660,16 @@ void Isolate::InitializeLoggingAndCounters() {
   }
 }
 
+namespace {
+void PrintBuiltinSizes(Isolate* isolate) {
+  Builtins* builtins = isolate->builtins();
+  for (int i = 0; i < Builtins::builtin_count; i++) {
+    const char* name = builtins->name(i);
+    Code* code = builtins->builtin(static_cast<Builtins::Name>(i));
+    PrintF(stdout, "%s: %d\n", name, code->instruction_size());
+  }
+}
+}  // namespace
 
 bool Isolate::Init(Deserializer* des) {
   TRACE_ISOLATE(init);
@@ -2799,6 +2809,8 @@ bool Isolate::Init(Deserializer* des) {
   delete setup_delegate_;
   setup_delegate_ = nullptr;
 
+  if (FLAG_print_builtin_size) PrintBuiltinSizes(this);
+
   // Finish initialization of ThreadLocal after deserialization is done.
   clear_pending_exception();
   clear_pending_message();