DevTools: [CSS] remove CSS Regions experiment from DevTools.

Source/core/inspector/InspectorInstrumentation.idl

Index: Source/core/inspector/InspectorInstrumentation.idl
diff --git a/Source/core/inspector/InspectorInstrumentation.idl b/Source/core/inspector/InspectorInstrumentation.idl
index dc929693ed7829b5172d495439d58da9e523262a..7c0e6a242ea8ad7ce4f847a4bffa883d28f7ab01 100644
--- a/Source/core/inspector/InspectorInstrumentation.idl
+++ b/Source/core/inspector/InspectorInstrumentation.idl
@@ -118,18 +118,6 @@ interface InspectorInstrumentation {
     [DOM, Inline=FastReturn]
     void willPopShadowRoot([Keep] Element* host, ShadowRoot*);
 
-    [CSS, Inline=FastReturn]
-    void didCreateNamedFlow([Keep] Document*, NamedFlow*);
-
-    [CSS, Inline=FastReturn]
-    void willRemoveNamedFlow([Keep] Document*, NamedFlow*);
-
-    [CSS, Inline=FastReturn]
-    void didUpdateRegionLayout([Keep] Document*, NamedFlow*);
-
-    [CSS, Inline=FastReturn]
-    void didChangeRegionOverset([Keep] Document*, NamedFlow*);
-
     [DOMDebugger, Inline=FastReturn]
     void willSendXMLHttpRequest(ExecutionContext*, const String& url);