Bug 1499240 - clean up textbox.xml according to toolkit version of the file. r=Paenglab

https://hg.mozilla.org/mozilla-central/rev/5d283ff675b4
https://hg.mozilla.org/mozilla-central/rev/ef26c0022369

common/bindings/textbox.xml

@@ -17,7 +17,7 @@
    xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
    xmlns:xbl="http://www.mozilla.org/xbl">
 
-  <binding id="textbox" extends="xul:box" role="xul:textbox">
+  <binding id="textbox">
 
     <content>
       <children/>
@@ -28,7 +28,7 @@
       </xul:moz-input-box>
     </content>
 
-    <implementation implements="nsIDOMXULTextBoxElement, nsIDOMXULLabeledControlElement">
+    <implementation implements="nsIDOMXULLabeledControlElement">
       <!-- nsIDOMXULLabeledControlElement -->
       <field name="crop">""</field>
       <field name="image">""</field>