[Minibrowser] Find bar detaches from the bottom of the window on resi…

…zing

https://bugs.webkit.org/show_bug.cgi?id=245057
rdar://99722096

Reviewed by Tim Horton.

* Tools/MiniBrowser/mac/WK2BrowserWindowController.m:
(-[WK2BrowserWindowController setFindBarView:]):

The find bar in Minibrowser is intended to be anchored to the bottom window.
Specify `NSViewMaxYMargin` in the view’s autoresizing mask to indicate that the
top margin between the view and its superview is flexible.

Canonical link: https://commits.webkit.org/254368@main

Tools/MiniBrowser/mac/WK2BrowserWindowController.m

@@ -882,8 +882,10 @@ - (NSView *)findBarView
 - (void)setFindBarView:(NSView *)findBarView
 {
     _textFindBarView = findBarView;
+    _textFindBarView.autoresizingMask = NSViewMaxYMargin | NSViewWidthSizable;
+    _textFindBarView.frame = NSMakeRect(0, 0, containerView.bounds.size.width, _textFindBarView.frame.size.height);
+
     _findBarVisible = YES;
-    [_textFindBarView setFrame:NSMakeRect(0, 0, containerView.bounds.size.width, _textFindBarView.frame.size.height)];
 }
 
 - (BOOL)isFindBarVisible