[Mac] Fix ClassCastException when selecting a color in FontDialog

- See #1814

- Also use Java 17 instanceof pattern matching in this code block

Author: Phillipus

bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/widgets/Display.java

@@ -5988,9 +5988,10 @@ static long dialogProc(long id, long sel, long arg0) {
 
 	switch (Selector.valueOf(sel)) {
 		case sel_changeColor_: {
-			ColorDialog dialog = (ColorDialog)OS.JNIGetObject(jniRef[0]);
-			if (dialog == null) return 0;
-			dialog.changeColor(id, sel, arg0);
+			Object object = OS.JNIGetObject(jniRef[0]);
+			if (object instanceof ColorDialog colorDialog) {
+				colorDialog.changeColor(id, sel, arg0);
+			}
 			return 0;
 		}
 		case sel_changeFont_: {
@@ -6012,10 +6013,10 @@ static long dialogProc(long id, long sel, long arg0) {
 		}
 		case sel_windowWillClose_: {
 			Object object = OS.JNIGetObject(jniRef[0]);
-			if (object instanceof FontDialog) {
-				((FontDialog)object).windowWillClose(id, sel, arg0);
-			} else if (object instanceof ColorDialog) {
-				((ColorDialog)object).windowWillClose(id, sel, arg0);
+			if (object instanceof FontDialog fontDialog) {
+				fontDialog.windowWillClose(id, sel, arg0);
+			} else if (object instanceof ColorDialog colorDialog) {
+				colorDialog.windowWillClose(id, sel, arg0);
 			}
 			return 0;
 		}