Bug 958993 - taping Clear button under Options several times creates multiple modal prompts.r=mbrubeck

browser/metro/base/content/browser-ui.js

@@ -1104,6 +1104,9 @@ var BrowserUI = {
     let message = bundle.GetStringFromName("clearPrivateData.message");
     let clearbutton = bundle.GetStringFromName("clearPrivateData.clearButton");
 
+    let prefsClearButton = document.getElementById("prefs-clear-data");
+    prefsClearButton.disabled = true; 
+
     let buttonPressed = Services.prompt.confirmEx(
                           null,
                           title,
@@ -1120,6 +1123,8 @@ var BrowserUI = {
     if (buttonPressed === 0) {
       SanitizeUI.onSanitize();
     }
+
+    prefsClearButton.disabled = false;
   },
 };