Moved initialization of a static map to the static initialization block (#12270)

Change-Id: I82c77edf5c17c712350cb64831b305b4c8363cf7

server/src/com/vaadin/ui/DateField.java

@@ -152,7 +152,8 @@ public class DateField extends AbstractField<Date> implements
     private String dateOutOfRangeMessage = "Date is out of allowed range";
 
     private DateRangeValidator currentRangeValidator;
-    {
+
+    static {
         variableNameForResolution.put(Resolution.SECOND, "sec");
         variableNameForResolution.put(Resolution.MINUTE, "min");
         variableNameForResolution.put(Resolution.HOUR, "hour");