[InputEvent] Don't modify selection when transpose was canceled

third_party/WebKit/LayoutTests/fast/events/inputevents/inputevent-transpose.html

Index: third_party/WebKit/LayoutTests/fast/events/inputevents/inputevent-transpose.html
diff --git a/third_party/WebKit/LayoutTests/fast/events/inputevents/inputevent-transpose.html b/third_party/WebKit/LayoutTests/fast/events/inputevents/inputevent-transpose.html
index b87a4bd2edfa76190f15e224ad3cae333420ad77..115039f2d9e9733fd883baa1047f91d458ef77a3 100644
--- a/third_party/WebKit/LayoutTests/fast/events/inputevents/inputevent-transpose.html
+++ b/third_party/WebKit/LayoutTests/fast/events/inputevents/inputevent-transpose.html
@@ -1,6 +1,7 @@
 <title>InputEvent: macOS Transpose</title>
 <script src="../../../resources/testharness.js"></script>
 <script src="../../../resources/testharnessreport.js"></script>
+<script src='../../../editing/assert_selection.js'></script>
 <div id="editable" contenteditable></div>
 <textarea id="txt"></textarea>
 <script>
@@ -9,7 +10,8 @@ test(() => {
 
     let eventRecorder = '';
     document.addEventListener('beforeinput', event => {
-        eventRecorder += `beforeinput-${event.inputType}-${event.data}-`;
+        const range = event.getTargetRanges()[0];
+        eventRecorder += `beforeinput-${event.inputType}-${event.data}-${range.startOffset}-${range.endOffset}-`;
     });
     document.addEventListener('input', event => {
         eventRecorder += `input-${event.inputType}`;
@@ -25,7 +27,7 @@ test(() => {
     eventRecorder = '';
     testRunner.execCommand('transpose');
     assert_equals(editable.innerHTML, 'acb');
-    assert_equals(eventRecorder, 'beforeinput-insertTranspose-cb-input-insertTranspose');
+    assert_equals(eventRecorder, 'beforeinput-insertTranspose-cb-1-3-input-insertTranspose');
 }, 'Transpose on contenteditable');
 
 test(() => {
@@ -50,4 +52,19 @@ test(() => {
     assert_equals(txt.value, 'acb');
     assert_equals(eventRecorder, 'beforeinput-insertTranspose-cb-input-insertTranspose');
 }, 'Transpose on <textarea>');
+
+test(() => {
+    assert_not_equals(window.testRunner, undefined, 'This test requires testRunner.');
+
+    assert_selection(
+        '<div contenteditable id="editable1">a|bc</div>',
+        selection => {
+            const editable1 = selection.document.getElementById('editable1');
+            editable1.addEventListener('beforeinput', event => {
+                event.preventDefault();
+            });
+            testRunner.execCommand('transpose');
+        },
+        '<div contenteditable id="editable1">a|bc</div>');
+}, 'Transpose should not modify selection when canceled');
 </script>