Add a nbsp at the the end of the text when the next text has a leading space.

third_party/WebKit/LayoutTests/editing/inserting/insert-space.html

Index: third_party/WebKit/LayoutTests/editing/inserting/insert-space.html
diff --git a/third_party/WebKit/LayoutTests/editing/inserting/insert-space.html b/third_party/WebKit/LayoutTests/editing/inserting/insert-space.html
index 778ca82f08f38f3fa85319cb9a5d38a9b8243cae..4c2c31454883fbf9399b36e70af311ada43cf5f9 100644
--- a/third_party/WebKit/LayoutTests/editing/inserting/insert-space.html
+++ b/third_party/WebKit/LayoutTests/editing/inserting/insert-space.html
@@ -34,4 +34,17 @@ test(() => assert_selection(
   },
   '<div contenteditable><p id="para">A\u00A0|</p></div>'),
   'Insert a &nbsp; instead of plain space when it is inserted before the empty text node');
+
+test(() => assert_selection(
+  '<div contenteditable><p id="para"></p></div>',
+  selection => {
+   var para = selection.document.getElementById('para');

[yosin_UTC9, 2016/10/20 01:29:17]

nit: Please fix indentation; one more space before |var|.

+    para.appendChild(selection.document.createTextNode('A'));
+    para.appendChild(selection.document.createTextNode(' B'));
+    selection.collapse(para.firstChild, 1);
+
+    selection.document.execCommand('insertText', false, ' ');
+  },
+  '<div contenteditable><p id="para">A\u00A0| B</p></div>'),
+  'Insert a &nbsp; instead of plain space when it is inserted before the text node that has a leading plain space');
 </script>