Ignore button mouse enter for new tab button

chrome/app/nibs/BrowserWindow.xib

 <?xml version="1.0" encoding="UTF-8"?>
 <archive type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="7.10">
         <data>
                 <int key="IBDocument.SystemTarget">1050</int>
                 <string key="IBDocument.SystemVersion">10K549</string>
                 <string key="IBDocument.InterfaceBuilderVersion">851</string>
                 <string key="IBDocument.AppKitVersion">1038.36</string>
                 <string key="IBDocument.HIToolboxVersion">461.00</string>
                 <object class="NSMutableDictionary" key="IBDocument.PluginVersions">
                         <string key="NS.key.0">com.apple.InterfaceBuilder.CocoaPlugin</string>
@@ skipping 267 matching lines @@
                                         <real value="0.0"/>
                                         <real value="0.0"/>
                                         <string>{{439, 576}, {483, 37}}</string>
                                         <string>com.apple.InterfaceBuilder.CocoaPlugin</string>
                                         <boolean value="YES"/>
                                         <string>NewTabButton</string>
                                         <string>com.apple.InterfaceBuilder.CocoaPlugin</string>
                                         <object class="NSAffineTransform">
                                                 <bytes key="NSTransformStruct">P4AAAL+AAABDk4AAwcgAAA</bytes>
                                         </object>
-                                        <string>ImageButtonCell</string>
+                                        <string>NewTabButtonCell</string>
                                         <string>com.apple.InterfaceBuilder.CocoaPlugin</string>
                                         <string>com.apple.InterfaceBuilder.CocoaPlugin</string>
                                 </object>
                         </object>
                         <object class="NSMutableDictionary" key="unlocalizedProperties">
                                 <bool key="EncodedWithXMLCoder">YES</bool>
                                 <reference key="dict.sortedKeys" ref="0"/>
                                 <object class="NSMutableArray" key="dict.values">
                                         <bool key="EncodedWithXMLCoder">YES</bool>
                                 </object>
@@ skipping 968 matching lines @@
                 </object>
                 <object class="NSMutableDictionary" key="IBDocument.PluginDeclaredDevelopmentDependencies">
                         <string key="NS.key.0">com.apple.InterfaceBuilder.CocoaPlugin.InterfaceBuilder3</string>
                         <integer value="3000" key="NS.object.0"/>
                 </object>
                 <bool key="IBDocument.PluginDeclaredDependenciesTrackSystemTargetVersion">YES</bool>
                 <string key="IBDocument.LastKnownRelativeProjectPath">../../chrome.xcodeproj</string>
                 <int key="IBDocument.defaultPropertyAccessControl">3</int>
         </data>
 </archive>