   setupMutationObserver: ->
     @observer = new MutationObserver (mutations) =>
       for mutation in mutations
-        @handleMutation mutation.oldValue, @getValue()
+        oldValue = mutation.oldValue
+        newValue = @getValue()
+        return if oldValue isnt newValue
+        @handleMutation oldValue, newValue
     params =
       attributes: true,
       attributeOldValue: true,

    else
      ''

  handleMutation: (oldValue, newValue) ->
    # Once we have navigated, we don't allow clearing the src attribute.
    # Once <webview> enters a navigated state, it cannot return to a

  # Changes the attribute's value without triggering its mutation handler.
  setValueIgnoreMutation: (value) ->
    @ignoreMutation = true
    @setValue value
    @ignoreMutation = false

  # Defines this attribute as a property on the webview node.
