Remove support for the keygen tag

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

Index: third_party/WebKit/Source/core/frame/Deprecation.cpp
diff --git a/third_party/WebKit/Source/core/frame/Deprecation.cpp b/third_party/WebKit/Source/core/frame/Deprecation.cpp
index 153099cf88ca689150193141845bf272952897c4..bc1957ee6b1e1dd1f86ce180f6554cf3d9097b10 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -369,9 +369,6 @@ String Deprecation::deprecationMessage(UseCounter::Feature feature) {
       return replacedBy("'Performance.onwebkitresourcetimingbufferfull'",
                         "'Performance.onresourcetimingbufferfull'");
 
-    case UseCounter::HTMLKeygenElement:
-      return willBeRemoved("The <keygen> element", M57, "5716060992962560");
-
     case UseCounter::EncryptedMediaAllSelectedContentTypesMissingCodecs:
       return String::format(
           "EME requires that contentType strings accepted by "