Fix handling of {undo: 'skip'} in TextEditor.insertText

Signed-off-by: Nathan Sobo <nathan@github.com>

spec/text-editor-spec.js

@@ -3507,13 +3507,16 @@ describe('TextEditor', () => {
       })
 
       describe("when the undo option is set to 'skip'", () => {
-        beforeEach(() => editor.setSelectedBufferRange([[1, 2], [1, 2]]))
-
-        it('does not undo the skipped operation', () => {
-          let range = editor.insertText('x')
-          range = editor.insertText('y', {undo: 'skip'})
+        it('groups the change with the previous change for purposes of undo and redo', () => {
+          editor.setSelectedBufferRanges([
+            [[0, 0], [0, 0]],
+            [[1, 0], [1, 0]]
+          ])
+          editor.insertText('x')
+          editor.insertText('y', {undo: 'skip'})
           editor.undo()
-          expect(buffer.lineForRow(1)).toBe('  yvar sort = function(items) {')
+          expect(buffer.lineForRow(0)).toBe('var quicksort = function () {')
+          expect(buffer.lineForRow(1)).toBe('  var sort = function(items) {')
         })
       })
     })

src/text-editor.js

@@ -1330,15 +1330,24 @@ class TextEditor {
   insertText (text, options = {}) {
     if (!this.emitWillInsertTextEvent(text)) return false
 
+    let groupLastChanges = false
+    if (options.undo === 'skip') {
+      options = Object.assign({}, options)
+      delete options.undo
+      groupLastChanges = true
+    }
+
     const groupingInterval = options.groupUndo ? this.undoGroupingInterval : 0
     if (options.autoIndentNewline == null) options.autoIndentNewline = this.shouldAutoIndent()
     if (options.autoDecreaseIndent == null) options.autoDecreaseIndent = this.shouldAutoIndent()
-    return this.mutateSelectedText(selection => {
+    const result = this.mutateSelectedText(selection => {
       const range = selection.insertText(text, options)
       const didInsertEvent = {text, range}
       this.emitter.emit('did-insert-text', didInsertEvent)
       return range
     }, groupingInterval)
+    if (groupLastChanges) this.buffer.groupLastChanges()
+    return result
   }
 
   // Essential: For each selection, replace the selected text with a newline.