First implementation of lazily cached accessor for DOM attributes.

third_party/WebKit/Source/core/html/HTMLElement.idl

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
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 // https://html.spec.whatwg.org/#htmlelement
 [HTMLConstructor]
 interface HTMLElement : Element {
     // metadata attributes
-    [CEReactions, Reflect] attribute DOMString title;
-    [CEReactions, Reflect] attribute DOMString lang;
+    [CEReactions, Reflect, CachedAccessor=Lazy] attribute DOMString title;

[Yuki, 2017/05/09 06:06:31]

Just curious, are |title| and |lang| so important?

I understand |id| is quite often used and worth using the cached accessor.  But
I didn't imagine that |title| and |lang| are heavily used.

[nverne, 2017/05/10 02:11:49]

haraken@ said these were good test cases for the mechanism itself. This plan is
to migrate lots of DOM properties to lazy caching, and these three are a
reasonable start. We can always revisit the choices of which attributes deserve
caching in future.

+    [CEReactions, Reflect, CachedAccessor=Lazy] attribute DOMString lang;
     [CEReactions] attribute boolean translate;
     [CEReactions] attribute DOMString dir;
     [SameObject, PerWorldBindings] readonly attribute DOMStringMap dataset;
 
     // user interaction
     [CEReactions, Reflect] attribute boolean hidden;
     void click();
     [CEReactions, CustomElementCallbacks] attribute long tabIndex;
     void focus();
     void blur();
@@ skipping 19 matching lines @@
     // CSS Object Model (CSSOM)
     // https://dev.w3.org/csswg/cssom/#the-elementcssinlinestyle-interface
     [SameObject, PerWorldBindings, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
 
     // Non-standard APIs
     [TreatNullAs=NullString, CEReactions, CustomElementCallbacks, RaisesException=Setter, MeasureAs=HTMLElementInnerText] attribute DOMString innerText;
     [TreatNullAs=NullString, CEReactions, CustomElementCallbacks, RaisesException=Setter, MeasureAs=HTMLElementOuterText] attribute DOMString outerText;
 };
 
 HTMLElement implements GlobalEventHandlers;