Remove support for -webkit-canvas and Document.getCSSCanvasContext.

third_party/WebKit/Source/core/frame/UseCounter.cpp

 /*
  * 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 880 matching lines @@
 
     case GeolocationInsecureOrigin:
         return "getCurrentPosition() and watchPosition() are deprecated on insecure origins, and support will be removed in the future. You should consider switching your application to a secure origin, such as HTTPS. See https://goo.gl/rStTGz for more details.";
 
     case GetUserMediaInsecureOrigin:
         return "getUserMedia() no longer works on insecure origins. To use this feature, you should consider switching your application to a secure origin, such as HTTPS. See https://goo.gl/rStTGz for more details.";
 
     case EncryptedMediaInsecureOrigin:
         return "requestMediaKeySystemAccess() is deprecated on insecure origins in the specification. Support will be removed in the future. You should consider switching your application to a secure origin, such as HTTPS. See https://goo.gl/rStTGz for more details.";
 
-    case DocumentGetCSSCanvasContext:
-        return "The -webkit-canvas CSS feature is deprecated. Please use a positioned <canvas> element instead.";
-
     case ElementCreateShadowRootMultiple:
         return "Calling Element.createShadowRoot() for an element which already hosts a shadow root is deprecated. See https://www.chromestatus.com/features/4668884095336448 for more details.";
 
     case ElementCreateShadowRootMultipleWithUserAgentShadowRoot:
         return "Calling Element.createShadowRoot() for an element which already hosts a user-agent shadow root is deprecated. See https://www.chromestatus.com/features/4668884095336448 for more details.";
 
     case CSSDeepCombinator:
         return "/deep/ combinator is deprecated. See https://www.chromestatus.com/features/6750456638341120 for more details.";
 
     case CSSSelectorPseudoShadow:
@@ skipping 69 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        https://crbug.com/242125
     if (sheetContents && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace blink