Two related changes that both affect how cursor positions might change on single line edits.

dart/tests/try/cursor_position_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // SharedOptions=--package-root=sdk/lib/_internal/
 
 // Test that cursor positions are correctly updated after adding new content.
 
 import 'test_try.dart';
 
 void main() {
   InteractionManager interaction = mockTryDartInteraction();
 
+  TestCase twoLines =
+      new TestCase('Test adding two lines programmatically.', () {
+        clearEditorPaneWithoutNotifications();
+        mainEditorPane.appendText('\n\n');
+        Text text = mainEditorPane.firstChild;
+        window.getSelection().collapse(text, 1);
+        checkSelectionIsCollapsed(text, 1);
+      }, checkAtBeginningOfSecondLine);
+
   runTests(<TestCase>[
+    twoLines,
 
-    new TestCase('Test adding two lines programmatically.', () {
-      clearEditorPaneWithoutNotifications();
-      mainEditorPane.appendText('\n\n');
-      Text text = mainEditorPane.firstChild;
-      window.getSelection().collapse(text, 1);
-      checkSelectionIsCollapsed(text, 1);
-    }, checkAtBeginningOfSecondLine),
+    new TestCase('Test adding a new text node.', () {
+      // This test relies on the previous test leaving two lines.
+      Text text = new Text('fisk');
+      window.getSelection().getRangeAt(0).insertNode(text);
+      window.getSelection().collapse(text, text.length);
+      checkSelectionIsCollapsed(text, text.length);
+    }, checkAtEndOfSecondLineWithFisk),
+
+    twoLines,
+
+    new TestCase('Test adding a new wrapped text node.', () {
+      // This test relies on the previous test leaving two lines.
+      Text text = new Text('fisk');
+      Node node = new SpanElement()..append(text);
+      window.getSelection().getRangeAt(0).insertNode(node);
+      window.getSelection().collapse(text, text.length);
+      checkSelectionIsCollapsed(text, text.length);
+    }, checkAtEndOfSecondLineWithFisk),
 
     new TestCase('Test adding a new line with mock key event.', () {
       clearEditorPaneWithoutNotifications();
       checkSelectionIsCollapsed(mainEditorPane, 0);
       simulateEnterKeyDown(interaction);
     }, checkAtBeginningOfSecondLine),
 
   ]);
 }
 
@@ skipping 13 matching lines @@
   Expect.equals(
       expectedLineCount, mainEditorPane.nodes.length,
       'mainEditorPane.nodes.length');
 }
 
 void checkAtBeginningOfSecondLine() {
   checkLineCount(2);
   checkSelectionIsCollapsed(mainEditorPane.nodes[1].firstChild, 0);
 }
 
+void checkAtEndOfSecondLineWithFisk() {
+  checkLineCount(2);
+  SpanElement secondLine = mainEditorPane.nodes[1];
+  Text text = secondLine.firstChild.firstChild;
+  Expect.stringEquals('fisk', text.text);
+  Expect.equals(4, text.length);
+  Text newline = secondLine.firstChild.nextNode;
+  Expect.equals(newline, secondLine.lastChild);
+  checkSelectionIsCollapsed(newline, 0);
+}
+
 class MockKeyboardEvent extends KeyEvent {
   final int keyCode;
 
   MockKeyboardEvent(String type, {int keyCode})
       : this.keyCode = keyCode,
         super.wrap(new KeyEvent(type, keyCode: keyCode));
 
   bool getModifierState(String keyArgument) => false;
 }