Make customElements.define faster

third_party/WebKit/Source/core/dom/custom/README.md

Index: third_party/WebKit/Source/core/dom/custom/README.md
diff --git a/third_party/WebKit/Source/core/dom/custom/README.md b/third_party/WebKit/Source/core/dom/custom/README.md
index a85cf911b1393a09c26adbfe48cccc4bd5afd87d..c0af263f235bdd231c9a9f9ca7b2eb11c89d5912 100644
--- a/third_party/WebKit/Source/core/dom/custom/README.md
+++ b/third_party/WebKit/Source/core/dom/custom/README.md
@@ -51,14 +51,16 @@ the definition to use.
 
 ### Memory Management
 
-Once defined, custom element constructors and prototypes have to be
-kept around indefinitely because they could be created in future by
-the parser. On the other hand, we must not leak when a window can no
-longer run script.
-
-We use a V8HiddenValue on the CustomElementRegistry wrapper which
-points to a map that keeps constructors and prototypes alive. See
-ScriptCustomElementDefinition.
+CustomElementRegistry
+implements
+[wrapper tracing](../../../bindings/core/v8/TraceWrapperReference.md)
+
+CustomElementDefinition, ScriptCustomElementDefinition hold onto the
+callbacks, etc. directly. They become TraceWrapperBase.
+
+Each V8PerContextData has a V8PrivateProperty identifying the custom
+element. The private property stores an int index into the
+CustomElementsRegistry list of definitions.
 
 ## Style Guide