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

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

Index: third_party/WebKit/Source/core/frame/UseCounter.cpp
diff --git a/third_party/WebKit/Source/core/frame/UseCounter.cpp b/third_party/WebKit/Source/core/frame/UseCounter.cpp
index 3a84f0065ba222f4a34fc20cc15dcfc81058979d..efec169dd9f2a50e8e39e050ad70d5a7c8e91b3f 100644
--- a/third_party/WebKit/Source/core/frame/UseCounter.cpp
+++ b/third_party/WebKit/Source/core/frame/UseCounter.cpp
@@ -898,9 +898,6 @@ String UseCounter::deprecationMessage(Feature feature)
     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.";