Handle TextEditorElement::focus() while parent is being attached

Fixes atom/autocomplete#61

spec/text-editor-element-spec.coffee

@@ -98,6 +98,22 @@ describe "TextEditorElement", ->
         document.body.focus()
         expect(blurCalled).toBe true
 
+    describe "when focused while a parent node is being attached to the DOM", ->
+      class ElementThatFocusesChild extends HTMLDivElement
+        attachedCallback: ->
+          @firstChild.focus()
+
+      document.registerElement("element-that-focuses-child",
+        prototype: ElementThatFocusesChild.prototype
+      )
+
+      it "proxies the focus event to the hidden input", ->
+        element = new TextEditorElement
+        parentElement = document.createElement("element-that-focuses-child")
+        parentElement.appendChild(element)
+        jasmineContent.appendChild(parentElement)
+        expect(element.shadowRoot.activeElement).toBe element.shadowRoot.querySelector('input')
+
   describe "when the themes finish loading", ->
     [themeReloadCallback, initialThemeLoadComplete, element] = []
 

src/text-editor-element.coffee

@@ -63,7 +63,8 @@ class TextEditorElement extends HTMLElement
     @buildModel() unless @getModel()?
     @mountComponent() unless @component?.isMounted()
     @component.checkForVisibilityChange()
-    @focus() if @focusOnAttach
+    if this is document.activeElement
+      @focused()
     @emitter.emit("did-attach")
 
   detachedCallback: ->
@@ -128,10 +129,7 @@ class TextEditorElement extends HTMLElement
     @component = null
 
   focused: ->
-    if @component?
-      @component.focused()
-    else
-      @focusOnAttach = true
+    @component?.focused()
 
   blurred: (event) ->
     unless @useShadowDOM