Harden the Chrome storage API lib.

Clear/delete should clear/delete data that's about to get set.

lib/$.coffee

@@ -228,29 +228,40 @@ $.localKeys = [
   'usercss'
 ]
 # https://developer.chrome.com/extensions/storage.html
-$.delete = (keys) ->
+do ->
+  items =
+    local: {}
+    sync:  {}
+
+  $.delete = (keys) ->
+    if typeof keys is 'string'
+      keys = [keys]
+    for key in keys
+      delete items.local[key]
+      delete items.sync[key]
     chrome.storage.sync.remove keys
-$.get = (key, val, cb) ->
+
+  $.get = (key, val, cb) ->
     if typeof cb is 'function'
-    items = $.item key, val
+      data = $.item key, val
     else
-    items = key
+      data = key
       cb = val
 
     localItems = null
     syncItems  = null
-  for key, val of items
+    for key, val of data
       if key in $.localKeys
         (localItems or= {})[key] = val
       else
         (syncItems  or= {})[key] = val
 
     count = 0
-  done  = (item) ->
+    done  = (result) ->
       if chrome.runtime.lastError
         c.error chrome.runtime.lastError.message
-    $.extend items, item
+      $.extend data, result
-    cb items unless --count
+      cb data unless --count
 
     if localItems
       count++
@@ -258,12 +269,8 @@ $.get = (key, val, cb) ->
     if syncItems
       count++
       chrome.storage.sync.get  syncItems,  done
-$.set = do ->
-  items =
-    sync: {}
-    local: {}
-  timeout = {}
 
+  timeout = {}
   setArea = (area) ->
     data = items[area]
     return if !Object.keys(data).length or timeout[area]
@@ -277,11 +284,11 @@ $.set = do ->
       delete timeout[area]
     items[area] = {}
 
-  setAll = $.debounce 5 * $.SECOND, ->
+  setAll = $.debounce $.SECOND, ->
     setArea 'local'
     setArea 'sync'
 
-  (key, val) ->
+  $.set = (key, val) ->
     if typeof key is 'string'
       items.sync[key] = val
     else
@@ -290,7 +297,10 @@ $.set = do ->
       items.local[key] = items.sync[key]
       delete items.sync[key]
     setAll()
-$.clear = (cb) ->
+
+  $.clear = (cb) ->
+    items.local = {}
+    items.sync  = {}
     count = 2
     done  = ->
       if chrome.runtime.lastError