Always render hidden input

This avoids mysterious timing issues in which the editor gets a 'focus'
event in a state where `isVisible` returns false. If we always render
the hidden input, we can always focus it.

Signed-off-by: Antonio Scandurra <as-cii@github.com>

spec/text-editor-element-spec.js

@@ -203,6 +203,22 @@ describe('TextEditorElement', () => {
         expect(document.activeElement).toBe(element.querySelector('input'))
       })
     })
+
+    describe('if focused when invisible due to a zero height and width', () => {
+      it('focuses the hidden input and does not throw an exception', () => {
+        const parentElement = document.createElement('div')
+        parentElement.style.position = 'absolute'
+        parentElement.style.width = '0px'
+        parentElement.style.height = '0px'
+
+        const element = buildTextEditorElement({attach: false})
+        parentElement.appendChild(element)
+        jasmineContent.appendChild(parentElement)
+
+        element.focus()
+        expect(document.activeElement).toBe(element.component.getHiddenInput())
+      })
+    })
   })
 
   describe('::setModel', () => {

src/text-editor-component.js

@@ -552,6 +552,7 @@ class TextEditorComponent {
       ]
     } else {
       children = [
+        this.renderCursorsAndInput(),
         this.renderBlockDecorationMeasurementArea(),
         this.renderCharacterMeasurementLine()
       ]
@@ -1449,16 +1450,14 @@ class TextEditorComponent {
       this.scheduleUpdate()
     }
 
-    const {hiddenInput} = this.refs.cursorsAndInput.refs
-    hiddenInput.focus()
+    this.getHiddenInput().focus()
   }
 
   // Called by TextEditorElement so that this function is always the first
   // listener to be fired, even if other listeners are bound before creating
   // the component.
   didBlur (event) {
-    const {cursorsAndInput} = this.refs
-    if (cursorsAndInput && event.relatedTarget === cursorsAndInput.refs.hiddenInput) {
+    if (event.relatedTarget === this.getHiddenInput()) {
       event.stopImmediatePropagation()
     }
   }