Fix Try Dart newline handling on IE11.

site/try/src/interaction_manager.dart

Index: site/try/src/interaction_manager.dart
===================================================================
--- site/try/src/interaction_manager.dart	(revision 39473)
+++ site/try/src/interaction_manager.dart	(working copy)
@@ -394,7 +394,13 @@
             selection.collapse(text, offset + 1);
           } else if (node is Element) {
             node.appendText('\n\n');
-            selection.collapse(node.firstChild, 1);
+            if (node.firstChild is Text) {
+              selection.collapse(node.firstChild, 1);
+            } else {
+              // This else-branch accomodates IE11, which
+              // puts <BR> instead of '\n' in content-editable Divs.
+              selection.collapse(node, 1);

[ahe, 2014/08/22 09:46:52]

How does this interact with getText in shadow_root.dart. In particular, I wonder
what would happen if IE supported shadow DOM. Concretely:

What is contents of node.text?

[aam-me, 2014/08/22 12:05:14]

By the time we get to that getText <br>'s are gone, replaced with Text('\n') in
normalizeMutationRecords.
node is <div> with textContent='', innerHtml='<br><br>', and three children: BR,
BR, Text(with textContent.text='')

[ahe, 2014/08/22 12:13:44]

In other words, this wouldn't work if IE supported shadow DOM :-(

Would this work:

node.append(new Text()..insertData('\n\n'));

+            }
           } else {
             window.console
                 ..error('Unexpected node')