Bug 1405875 - Remove unused contentViewerFile property from browser and tabbrowser XBL bindings. r=Gijs

This helps to make nsIContentViewerFile unused so that we can remove it
later in this patch series.

MozReview-Commit-ID: I0LvygpnCx8

browser/base/content/tabbrowser.xml

@@ -5399,10 +5399,6 @@
                 onget="return this.mCurrentBrowser.contentViewerEdit;"
                 readonly="true"/>
 
-      <property name="contentViewerFile"
-                onget="return this.mCurrentBrowser.contentViewerFile;"
-                readonly="true"/>
-
       <property name="contentDocument"
                 onget="return this.mCurrentBrowser.contentDocument;"
                 readonly="true"/>

toolkit/content/widgets/browser.xml

@@ -488,10 +488,6 @@
                 onget="return this.docShell.contentViewer.QueryInterface(Components.interfaces.nsIContentViewerEdit);"
                 readonly="true"/>
 
-      <property name="contentViewerFile"
-                onget="return this.docShell.contentViewer.QueryInterface(Components.interfaces.nsIContentViewerFile);"
-                readonly="true"/>
-
       <property name="contentDocument"
                 onget="return this.webNavigation.document;"
                 readonly="true"/>