Handle addition/removal of ‘gutter-hidden’ attribute

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

spec/text-editor-element-spec.coffee

@@ -30,6 +30,17 @@ describe "TextEditorElement", ->
       element = jasmineContent.firstChild
       expect(element.getModel().getText()).toBe 'testing'
 
+  describe "when attributes change", ->
+    it "honors addition/removal of the 'gutter-hidden' attribute", ->
+      element = new TextEditorElement
+      expect(element.getModel().isGutterVisible()).toBe true
+
+      element.setAttributeNode(document.createAttribute("gutter-hidden"))
+      expect(element.getModel().isGutterVisible()).toBe false
+
+      element.removeAttribute('gutter-hidden')
+      expect(element.getModel().isGutterVisible()).toBe true
+
   describe "when the model is assigned", ->
     it "adds the 'mini' attribute if .isMini() returns true on the model", ->
       element = new TextEditorElement

src/text-editor-element.coffee

@@ -71,6 +71,10 @@ class TextEditorElement extends HTMLElement
     @unmountComponent()
     @emitter.emit("did-detach")
 
+  attributeChangedCallback: (name, oldValue, newValue) ->
+    if name is 'gutter-hidden'
+      @getModel().setGutterVisible(not @hasAttribute('gutter-hidden'))
+
   initialize: (model) ->
     @setModel(model)
     this