Prune empty block scopes from scope tree

src/scopes.cc

 // Copyright 2011 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 313 matching lines @@
     // allocated during variable allocation.
     variables_.Declare(this,
                        isolate_->factory()->arguments_symbol(),
                        Variable::VAR,
                        true,
                        Variable::ARGUMENTS);
   }
 }
 
 
+Scope* Scope::FinalizeBlockScope() {
+  ASSERT(is_block_scope());
+  ASSERT(decls_.is_empty());
+  ASSERT(temps_.is_empty());
+  ASSERT(params_.is_empty());
+
+  if (num_var_or_const() > 0) return this;
+
+  // Remove this scope from outer scope.
+  for (int i = 0; i < outer_scope_->inner_scopes_.length(); i++) {
+    if (outer_scope_->inner_scopes_[i] == this) {
+      outer_scope_->inner_scopes_.Remove(i);
+      break;
+    }
+  }
+
+  // Reparent inner scopes.
+  for (int i = 0; i < inner_scopes_.length(); i++) {
+    outer_scope()->AddInnerScope(inner_scopes_[i]);
+  }
+
+  // Move unresolved variables
+  for (int i = 0; i < unresolved_.length(); i++) {
+    outer_scope()->unresolved_.Add(unresolved_[i]);
+  }
+
+  return NULL;
+}
+
+
 Variable* Scope::LocalLookup(Handle<String> name) {
   Variable* result = variables_.Lookup(name);
   if (result != NULL || scope_info_.is_null()) {
     return result;
   }
   // If we have a serialized scope info, we might find the variable there.
   //
   // We should never lookup 'arguments' in this scope as it is implicitly
   // present in every scope.
   ASSERT(*name != *isolate_->factory()->arguments_symbol());
@@ skipping 809 matching lines @@
   if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS &&
       !must_have_local_context) {
     num_heap_slots_ = 0;
   }
 
   // Allocation done.
   ASSERT(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
 }
 
 } }  // namespace v8::internal