Pass selectionsMarkerLayer on transact, undo and redo

To restore selections of change initiated editor on undo/redo.

src/text-editor.js

@@ -224,7 +224,7 @@ class TextEditor {
 
     this.defaultMarkerLayer = this.displayLayer.addMarkerLayer()
     if (!this.selectionsMarkerLayer) {
-      this.selectionsMarkerLayer = this.addMarkerLayer({maintainHistory: true, persistent: true})
+      this.selectionsMarkerLayer = this.addMarkerLayer({maintainHistory: true, persistent: true, role: 'selections'})
     }
 
     this.decorationManager = new DecorationManager(this)
@@ -1808,13 +1808,13 @@ class TextEditor {
 
   // Essential: Undo the last change.
   undo () {
-    this.avoidMergingSelections(() => this.buffer.undo())
+    this.avoidMergingSelections(() => this.buffer.undo({selectionsMarkerLayer: this.selectionsMarkerLayer}))
     this.getLastSelection().autoscroll()
   }
 
   // Essential: Redo the last change.
   redo () {
-    this.avoidMergingSelections(() => this.buffer.redo())
+    this.avoidMergingSelections(() => this.buffer.redo({selectionsMarkerLayer: this.selectionsMarkerLayer}))
     this.getLastSelection().autoscroll()
   }
 
@@ -1831,7 +1831,13 @@ class TextEditor {
   //   still 'groupable', the two transactions are merged with respect to undo and redo.
   // * `fn` A {Function} to call inside the transaction.
   transact (groupingInterval, fn) {
-    return this.buffer.transact(groupingInterval, fn)
+    const options = {selectionsMarkerLayer: this.selectionsMarkerLayer}
+    if (typeof groupingInterval === 'function') {
+      fn = groupingInterval
+    } else {
+      options.groupingInterval = groupingInterval
+    }
+    return this.buffer.transact(options, fn)
   }
 
   // Extended: Abort an open transaction, undoing any operations performed so far
@@ -1842,7 +1848,9 @@ class TextEditor {
   // with {::revertToCheckpoint} and {::groupChangesSinceCheckpoint}.
   //
   // Returns a checkpoint value.
-  createCheckpoint () { return this.buffer.createCheckpoint() }
+  createCheckpoint () {
+    return this.buffer.createCheckpoint({selectionsMarkerLayer: this.selectionsMarkerLayer})
+  }
 
   // Extended: Revert the buffer to the state it was in when the given
   // checkpoint was created.
@@ -1866,7 +1874,9 @@ class TextEditor {
   // * `checkpoint` The checkpoint from which to group changes.
   //
   // Returns a {Boolean} indicating whether the operation succeeded.
-  groupChangesSinceCheckpoint (checkpoint) { return this.buffer.groupChangesSinceCheckpoint(checkpoint) }
+  groupChangesSinceCheckpoint (checkpoint) {
+    return this.buffer.groupChangesSinceCheckpoint(checkpoint, {selectionsMarkerLayer: this.selectionsMarkerLayer})
+  }
 
   /*
   Section: TextEditor Coordinates