Re-render component when EditorView is reattached

Fixes #3640

spec/text-editor-component-spec.coffee

@@ -2259,6 +2259,11 @@ describe "TextEditorComponent", ->
       editor.setGrammar(atom.syntax.nullGrammar)
       expect(wrapperNode.dataset.grammar).toBe 'text plain null-grammar'
 
+  describe "detaching and reattaching the editor (regression)", ->
+    it "does not throw an exception", ->
+      wrapperView.detach()
+      wrapperView.attachToDom()
+
   buildMouseEvent = (type, properties...) ->
     properties = extend({bubbles: true, cancelable: true}, properties...)
     properties.detail ?= 1

src/text-editor-view.coffee

@@ -95,7 +95,8 @@ class TextEditorView extends View
         placeholderText: placeholderText
 
     props = defaults({@editor, parentView: this}, props)
-    @component = React.renderComponent(TextEditorComponent(props), @element)
+    @componentDescriptor = TextEditorComponent(props)
+    @component = React.renderComponent(@componentDescriptor, @element)
 
     node = @component.getDOMNode()
 
@@ -146,6 +147,7 @@ class TextEditorView extends View
     return unless onDom
     return if @attached
     @attached = true
+    @component = React.renderComponent(@componentDescriptor, @element) unless @component.isMounted()
     @component.checkForVisibilityChange()
 
     @focus() if @focusOnAttach