Fix incorrectly namespaced spacer elements. b=321402 r=mconnor a=blocking1.9+/M9

toolkit/mozapps/extensions/content/extensions.xml

@@ -230,7 +230,7 @@
             <xul:button class="uninstallHide themeButton useThemeButton" label="&cmd.useTheme.label;"
                         accesskey="&cmd.useTheme.accesskey;" tooltiptext="&cmd.useTheme.tooltip;"
                         command="cmd_useTheme"/>
-            <spacer flex="1"/>
+            <xul:spacer flex="1"/>
             <xul:button class="disableShow enableHide uninstallHide enableButton" label="&cmd.enable.label;"
                         accesskey="&cmd.enable.accesskey;" tooltiptext="&cmd.enable.tooltip;"
                         command="cmd_enable"/>

xpfe/components/console/resources/content/consoleBindings.xml

@@ -304,7 +304,7 @@
           <xul:box class="console-row-file" xbl:inherits="hidden=hideSource">
             <xul:label class="label" value="&errFile.label;"/>
             <xul:box class="console-error-source" xbl:inherits="url,line"/>
-            <spacer flex="1"/>
+            <xul:spacer flex="1"/>
             <xul:hbox class="lineNumberRow" xbl:inherits="line">
               <xul:label class="label" value="&errLine.label;"/>
               <xul:label class="label" xbl:inherits="value=line"/>