Move removing keyIdentifier to M54.

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 26f8c70d90a3ae592a9ff2ec364a84ae7264e33a..bd9f746d4977d903b55e332d2320b5113bf9f9b2 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -363,7 +363,7 @@ String Deprecation::deprecationMessage(UseCounter::Feature feature)
         return String::format("EME requires that contentType strings accepted by requestMediaKeySystemAccess() include codecs. Non-standard support for contentType strings without codecs will be removed in %s. Please specify the desired codec(s) as part of the contentType.", milestoneString(54));
 
     case UseCounter::V8KeyboardEvent_KeyIdentifier_AttributeGetter:
-        return willBeRemoved("'KeyboardEvent.keyIdentifier'", 53, "5316065118650368");
+        return willBeRemoved("'KeyboardEvent.keyIdentifier'", 54, "5316065118650368");
 
     case UseCounter::During_Microtask_SyncXHR:
         return willBeRemoved("Invoking 'send()' on a sync XHR during microtask execution", 54, "5647113010544640");