Rename ExperimentalShadowDOM runtime feature to ShadowDOM.

Source/core/dom/Element.idl

Index: Source/core/dom/Element.idl
diff --git a/Source/core/dom/Element.idl b/Source/core/dom/Element.idl
index fdd23357794cdb6940c255c314abae625e4dde02..bbf65a90b224e9ede51f835ae4a3972eaec9e7c8 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -101,9 +101,9 @@
     [RaisesException] boolean webkitMatchesSelector([Default=Undefined] optional DOMString selectors);
 
     // Shadow DOM API
-    [EnabledAtRuntime=experimentalShadowDOM, Reflect, PerWorldBindings] attribute DOMString pseudo;
-    [EnabledAtRuntime=experimentalShadowDOM, RaisesException] ShadowRoot createShadowRoot();
-    [EnabledAtRuntime=experimentalShadowDOM, PerWorldBindings] readonly attribute ShadowRoot shadowRoot;
+    [EnabledAtRuntime=ShadowDOM, Reflect, PerWorldBindings] attribute DOMString pseudo;
+    [EnabledAtRuntime=ShadowDOM, RaisesException] ShadowRoot createShadowRoot();
+    [EnabledAtRuntime=ShadowDOM, PerWorldBindings] readonly attribute ShadowRoot shadowRoot;
 
     // To-be-deprecated prefixed Shadow DOM API
     [Reflect=pseudo, ImplementedAs=pseudo, PerWorldBindings] attribute DOMString webkitPseudo;