Fix Try Dart newline handling on IE11.

site/try/src/interaction_manager.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.
 
 library trydart.interaction_manager;
 
 import 'dart:html';
 
 import 'dart:convert' show
     JSON;
@@ skipping 372 matching lines @@
           event.preventDefault();
           Node node = selection.anchorNode;
           if (node is Text) {
             Text text = node;
             int offset = selection.anchorOffset;
             // If at end-of-file, insert an extra newline.  The the extra
             // newline ensures that the next line isn't empty.  At least Chrome
             // behaves as if "\n" is just a single line. "\nc" (where c is any
             // character) is two lines, according to Chrome.
             String newline = isAtEndOfFile(text, offset) ? '\n\n' : '\n';
             text.insertData(offset, newline);

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

Does this work the same in IE and Chrome? If so, can we use text.insertData
instead of appendText?

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

I believe it does, but appendText is on Element, while insertData is on Text. We
are using appendText because there is no Text available.

             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')
                 ..dir(node);
           }
         }
         break;
       }
       case KeyCode.TAB: {
         Selection selection = window.getSelection();
@@ skipping 939 matching lines @@
     token = token.next;
     kind = token.kind;
   }
   return token;
 }
 
 String extractQuote(String string) {
   StringQuoting q = StringValidator.quotingFromString(string);
   return (q.raw ? 'r' : '') + (q.quoteChar * q.leftQuoteLength);
 }