Remove DialogElement runtime flag (status=stable)

Source/core/rendering/RenderTheme.cpp

Index: Source/core/rendering/RenderTheme.cpp
diff --git a/Source/core/rendering/RenderTheme.cpp b/Source/core/rendering/RenderTheme.cpp
index 5feb92bb22c1c1000114c7030e96363d349f2053..6efb87b899c1fb6aebe21bfdfd345762e396a314 100644
--- a/Source/core/rendering/RenderTheme.cpp
+++ b/Source/core/rendering/RenderTheme.cpp
@@ -406,11 +406,9 @@ bool RenderTheme::paintDecorations(RenderObject* o, const PaintInfo& paintInfo,
 String RenderTheme::extraDefaultStyleSheet()
 {
     StringBuilder runtimeCSS;
-    if (RuntimeEnabledFeatures::dialogElementEnabled()) {
-        runtimeCSS.appendLiteral("dialog:not([open]) { display: none; }");
-        runtimeCSS.appendLiteral("dialog { position: absolute; left: 0; right: 0; width: -webkit-fit-content; height: -webkit-fit-content; margin: auto; border: solid; padding: 1em; background: white; color: black;}");
-        runtimeCSS.appendLiteral("dialog::backdrop { position: fixed; top: 0; right: 0; bottom: 0; left: 0; background: rgba(0,0,0,0.1); }");
-    }
+    runtimeCSS.appendLiteral("dialog:not([open]) { display: none; }");
+    runtimeCSS.appendLiteral("dialog { position: absolute; left: 0; right: 0; width: -webkit-fit-content; height: -webkit-fit-content; margin: auto; border: solid; padding: 1em; background: white; color: black;}");
+    runtimeCSS.appendLiteral("dialog::backdrop { position: fixed; top: 0; right: 0; bottom: 0; left: 0; background: rgba(0,0,0,0.1); }");
 
     if (RuntimeEnabledFeatures::contextMenuEnabled()) {
         runtimeCSS.appendLiteral("menu[type=\"popup\" i] { display: none; }");