Remove outdated IE10 compatibility class (#12193)

Leftover from 0081286c8d

client/src/main/java/com/vaadin/client/event/PointerEventSupportImplIE10.java

@@ -1,34 +0,0 @@
-/*
- * Copyright 2000-2018 Vaadin Ltd.
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not
- * use this file except in compliance with the License. You may obtain a copy of
- * the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations under
- * the License.
- */
-package com.vaadin.client.event;
-
-import com.vaadin.client.event.PointerEvent.EventType;
-
-/**
- * Pointer event support class for IE 10 ("ms" prefixed pointer events).
- *
- * @since 7.2
- * @author Vaadin Ltd
- */
-public class PointerEventSupportImplIE10
-        extends PointerEventSupportImplModernIE {
-
-    @Override
-    public String getNativeEventName(EventType eventName) {
-        return "MS" + eventName;
-    }
-
-}