Make customElements.define faster

third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.cpp

Index: third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.cpp
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.cpp b/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.cpp
index 28a45e752735b2b9c175793219c9a9fdd2a05b1f..41610482c81044994d1a058f6949a9f5b23fbe48 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.cpp
@@ -4,6 +4,7 @@
 
 #include "core/dom/custom/CustomElementRegistry.h"
 
+#include <limits>
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptCustomElementDefinitionBuilder.h"
 #include "bindings/core/v8/ScriptPromise.h"
@@ -93,6 +94,8 @@ DEFINE_TRACE(CustomElementRegistry) {
 
 DEFINE_TRACE_WRAPPERS(CustomElementRegistry) {
   visitor->TraceWrappers(&CustomElementReactionStack::Current());
+  for (auto definition : definitions_)
+    visitor->TraceWrappers(definition);
 }
 
 CustomElementDefinition* CustomElementRegistry::define(
@@ -183,11 +186,15 @@ CustomElementDefinition* CustomElementRegistry::define(
   }
 
   CustomElementDescriptor descriptor(name, local_name);
-  CustomElementDefinition* definition = builder.Build(descriptor);
+  if (UNLIKELY(definitions_.size() >= std::numeric_limits<uint32_t>::max()))
+    return nullptr;
+  uint32_t id = definitions_.size() + 1;
+  CustomElementDefinition* definition = builder.Build(descriptor, id);
   CHECK(!exception_state.HadException());
   CHECK(definition->Descriptor() == descriptor);
-  DefinitionMap::AddResult result =
-      definitions_.insert(descriptor.GetName(), definition);
+  definitions_.emplace_back(
+      TraceWrapperMember<CustomElementDefinition>(this, definition));
+  DefinitionMap::AddResult result = nameIdMap_.insert(descriptor.GetName(), id);
   CHECK(result.is_new_entry);
 
   HeapVector<Member<Element>> candidates;
@@ -234,7 +241,7 @@ CustomElementDefinition* CustomElementRegistry::DefinitionFor(
 }
 
 bool CustomElementRegistry::NameIsDefined(const AtomicString& name) const {
-  return definitions_.Contains(name);
+  return nameIdMap_.Contains(name);
 }
 
 void CustomElementRegistry::Entangle(V0CustomElementRegistrationContext* v0) {
@@ -252,7 +259,12 @@ bool CustomElementRegistry::V0NameIsDefined(const AtomicString& name) {
 
 CustomElementDefinition* CustomElementRegistry::DefinitionForName(
     const AtomicString& name) const {
-  return definitions_.at(name);
+  return DefinitionForId(nameIdMap_.at(name));
+}
+
+CustomElementDefinition* CustomElementRegistry::DefinitionForId(
+    CustomElementDefinition::Id id) const {
+  return id ? definitions_[id - 1].Get() : nullptr;
 }
 
 void CustomElementRegistry::AddCandidate(Element* candidate) {