Bug 1510840 - Remove unused plugin strings r=jaws

Differential Revision: https://phabricator.services.mozilla.com/D13453

--HG--
extra : moz-landing-system : lando

browser/locales/en-US/chrome/browser/browser.dtd

@@ -1006,11 +1006,6 @@ you can use these alternative items. Otherwise, their values should be empty.  -
 <!ENTITY pluginNotification.showAll.label "Show All">
 <!ENTITY pluginNotification.showAll.accesskey "S">
 
-<!-- LOCALIZATION NOTE (pluginActivateNow.label, pluginActivateAlways.label, pluginBlockNow.label): These should be the same as the matching strings in browser.properties -->
-<!ENTITY pluginActivateNow.label "Allow Now">
-<!ENTITY pluginActivateAlways.label "Allow and Remember">
-<!ENTITY pluginBlockNow.label "Block Plugin">
-
 <!-- LOCALIZATION NOTE: (pluginNotification.width): This is used to determine the
      width of the plugin popup notification that can appear if a plugin has been
      blocked on a page. Should be wide enough to fit the pluginActivateNow.label

browser/locales/en-US/chrome/browser/browser.properties

@@ -298,22 +298,6 @@ keywordURIFixup.dismiss.accesskey=N
 
 pluginInfo.unknownPlugin=Unknown
 
-# LOCALIZATION NOTE (pluginActivateNow.label, pluginActivateAlways.label, pluginBlockNow.label): These should be the same as the matching strings in browser.dtd
-# LOCALIZATION NOTE (pluginActivateNow.label): This button will enable the
-# plugin in the current session for an short time (about an hour), auto-renewed
-# if the site keeps using the plugin.
-pluginActivateNow.label=Allow Now
-pluginActivateNow.accesskey=N
-# LOCALIZATION NOTE (pluginActivateAlways.label): This button will enable the
-# plugin for a long while (90 days), auto-renewed if the site keeps using the
-# plugin.
-pluginActivateAlways.label=Allow and Remember
-pluginActivateAlways.accesskey=R
-pluginBlockNow.label=Block Plugin
-pluginBlockNow.accesskey=B
-pluginContinue.label=Continue Allowing
-pluginContinue.accesskey=C
-
 # Flash activation doorhanger UI
 flashActivate.message=Do you want to allow Adobe Flash to run on this site? Only allow Adobe Flash on sites you trust.
 flashActivate.outdated.message=Do you want to allow an outdated version of Adobe Flash to run on this site? An outdated version can affect browser performance and security.