mac: Tell Panel.xib that PanelWindowCocoaImpl derives from NSWindow.

chrome/app/nibs/Panel.xib

Index: chrome/app/nibs/Panel.xib
diff --git a/chrome/app/nibs/Panel.xib b/chrome/app/nibs/Panel.xib
index e4849041476587ea717ca669777ff3e2687fc480..7b377001b00249c0dbb0216a910494a56a75f28a 100644
--- a/chrome/app/nibs/Panel.xib
+++ b/chrome/app/nibs/Panel.xib
@@ -12,8 +12,8 @@
 		</object>
 		<object class="NSMutableArray" key="IBDocument.EditedObjectIDs">
 			<bool key="EncodedWithXMLCoder">YES</bool>
-			<integer value="6"/>
 			<integer value="1"/>
+			<integer value="6"/>
 		</object>
 		<object class="NSArray" key="IBDocument.PluginDependencies">
 			<bool key="EncodedWithXMLCoder">YES</bool>
@@ -424,9 +424,9 @@
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
-					<string>{{995, 387}, {480, 270}}</string>
+					<string>{{995, 221}, {480, 270}}</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
-					<string>{{995, 387}, {480, 270}}</string>
+					<string>{{995, 221}, {480, 270}}</string>
 					<boolean value="NO"/>
 					<string>{196, 240}</string>
 					<string>{{357, 418}, {480, 270}}</string>
@@ -443,7 +443,7 @@
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
-					<string>{{980, 885}, {300, 22}}</string>
+					<string>{{685, 885}, {300, 22}}</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
 				</object>
 			</object>
@@ -676,6 +676,14 @@
 					<reference key="sourceIdentifier" ref="501324801"/>
 				</object>
 				<object class="IBPartialClassDescription">
+					<string key="className">PanelWindowCocoaImpl</string>
+					<string key="superclassName">NSWindow</string>
+					<object class="IBClassDescriptionSource" key="sourceIdentifier">
+						<string key="majorKey">IBUserSource</string>
+						<string key="minorKey"/>
+					</object>
+				</object>
+				<object class="IBPartialClassDescription">
 					<string key="className">PanelWindowControllerCocoa</string>
 					<string key="superclassName">NSWindowController</string>
 					<object class="NSMutableDictionary" key="outlets">