Destroy editors after text editor component specs

This only now became necessary because TokenizedBuffer now *always*
receives a reference to the Atom config on construction, and always
tries to read from it when isFoldableAtRow is called, which can happen
after test cleanup due to resize observers.

spec/text-editor-component-spec.js

@@ -25,6 +25,8 @@ document.registerElement('text-editor-component-test-element', {
   })
 })
 
+const editors = []
+
 describe('TextEditorComponent', () => {
   beforeEach(() => {
     jasmine.useRealClock()
@@ -35,6 +37,13 @@ describe('TextEditorComponent', () => {
     jasmine.attachToDOM(scrollbarStyle)
   })
 
+  afterEach(() => {
+    for (const editor of editors) {
+      editor.destroy()
+    }
+    editors.length = 0
+  })
+
   describe('rendering', () => {
     it('renders lines and line numbers for the visible region', async () => {
       const {component, element, editor} = buildComponent({rowsPerTile: 3, autoHeight: false})
@@ -4486,6 +4495,7 @@ function buildEditor (params = {}) {
   const editor = new TextEditor(editorParams)
   editor.testAutoscrollRequests = []
   editor.onDidRequestAutoscroll((request) => { editor.testAutoscrollRequests.push(request) })
+  editors.push(editor)
   return editor
 }