6887249: Get rid of double-check for isValid() idiom in validate() methods

Reviewed-by: art, dcherepanov

src/share/classes/java/awt/Container.java

@@ -1583,8 +1583,6 @@ public class Container extends Component {
      * @see #validateTree
      */
     public void validate() {
-        /* Avoid grabbing lock unless really necessary. */
-        if (!isValid() || descendUnconditionallyWhenValidating) {
         boolean updateCur = false;
         synchronized (getTreeLock()) {
             if ((!isValid() || descendUnconditionallyWhenValidating)
@@ -1612,7 +1610,6 @@ public class Container extends Component {
             updateCursorImmediately();
         }
     }
-    }
 
     /**
      * Indicates whether valid containers should also traverse their