Remove CSS regions support, keeping a bare minimum to support "region-based" multicol.

Source/core/frame/UseCounter.h

 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 223 matching lines @@
         CSSStyleDeclarationFloatPropertyName = 189, // Pending removal in CSSOM.
         InputTypeText = 190,
         InputTypeTextMaxLength = 191,
         InputTypePassword = 192,
         InputTypePasswordMaxLength = 193,
         SVGInstanceRoot = 194,
         ShowModalDialog = 195,
         PrefixedPageVisibility = 196,
         HTMLFrameElementLocation = 197,
         CSSStyleSheetInsertRuleOptionalArg = 198, // Inconsistent with the specification and other browsers.
-        CSSWebkitRegionAtRule = 199, // @region rule changed to ::region()
         DocumentBeforeUnloadRegistered = 200,
         DocumentBeforeUnloadFired = 201,
         DocumentUnloadRegistered = 202,
         DocumentUnloadFired = 203,
         SVGLocatableNearestViewportElement = 204,
         SVGLocatableFarthestViewportElement = 205,
         IsIndexElement = 206,
         HTMLHeadElementProfile = 207,
         OverflowChangedEvent = 208,
         SVGPointMatrixTransform = 209,
@@ skipping 101 matching lines @@
 
     void updateMeasurements();
 
     OwnPtr<BitVector> m_countBits;
     BitVector m_CSSFeatureBits;
 };
 
 } // namespace WebCore
 
 #endif // UseCounter_h