Improve the debugDumpFoo output (#6882)

packages/flutter/lib/src/foundation/print.dart

@@ -80,24 +80,27 @@ final RegExp _indentPattern = new RegExp('^ *(?:[-+*] |[0-9]+[.):] )?');
 enum _WordWrapParseMode { inSpace, inWord, atBreak }
 /// Wraps the given string at the given width.
 ///
-/// Wrapping occurs at space characters (U+0020). Lines that start
-/// with an octothorpe ("#", U+0023) are not wrapped (so for example,
-/// Dart stack traces won't be wrapped).
+/// Wrapping occurs at space characters (U+0020). Lines that start with an
+/// octothorpe ("#", U+0023) are not wrapped (so for example, Dart stack traces
+/// won't be wrapped).
 ///
-/// This is not suitable for use with arbitrary Unicode text. For
-/// example, it doesn't implement UAX #14, can't handle ideographic
-/// text, doesn't hyphenate, and so forth. It is only intended for
-/// formatting error messages.
+/// Subsequent lines attempt to duplicate the indentation of the first line, for
+/// example if the first line starts with multiple spaces. In addition, if a
+/// `wrapIndent` argument is provided, each line after the first is prefixed by
+/// that string.
 ///
-/// The default [debugPrint] implementation uses this for its line
-/// wrapping.
-Iterable<String> debugWordWrap(String message, int width) sync* {
+/// This is not suitable for use with arbitrary Unicode text. For example, it
+/// doesn't implement UAX #14, can't handle ideographic text, doesn't hyphenate,
+/// and so forth. It is only intended for formatting error messages.
+///
+/// The default [debugPrint] implementation uses this for its line wrapping.
+Iterable<String> debugWordWrap(String message, int width, { String wrapIndent: '' }) sync* {
   if (message.length < width || message[0] == '#') {
     yield message;
     return;
   }
   Match prefixMatch = _indentPattern.matchAsPrefix(message);
-  String prefix = ' ' * prefixMatch.group(0).length;
+  String prefix = wrapIndent + ' ' * prefixMatch.group(0).length;
   int start = 0;
   int startForLengthCalculations = 0;
   bool addPrefix = false;

packages/flutter/lib/src/rendering/object.dart

@@ -2410,7 +2410,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
     List<String> description = <String>[];
     debugFillDescription(description);
     result += description
-      .expand((String description) => description.split('\n'))
+      .expand((String description) => debugWordWrap(description, 65, wrapIndent: '  '))
       .map/*<String>*/((String line) => "$descriptionPrefix$line\n")
       .join();
     if (childrenDescription == '')

packages/flutter/lib/src/rendering/view.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:developer';
+import 'dart:io' show Platform;
 import 'dart:ui' as ui show Scene, SceneBuilder, window;
 
 import 'package:vector_math/vector_math_64.dart';
@@ -171,8 +172,14 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
   @override
   void debugFillDescription(List<String> description) {
     // call to ${super.debugFillDescription(prefix)} is omitted because the root superclasses don't include any interesting information for this class
+    assert(() {
+      description.add('debug mode enabled - ${Platform.operatingSystem}');
+      return true;
+    });
     description.add('window size: ${ui.window.physicalSize} (in physical pixels)');
     description.add('device pixel ratio: ${ui.window.devicePixelRatio} (physical pixels per logical pixel)');
     description.add('configuration: $configuration (in logical pixels)');
+    if (ui.window.semanticsEnabled)
+      description.add('semantics enabled');
   }
 }

packages/flutter/lib/src/widgets/framework.dart

@@ -2578,19 +2578,7 @@ abstract class Element implements BuildContext {
     }
     if (node != null)
       chain.add('\u22EF');
-    String result = '';
-    String line = '';
-    for (String link in chain) {
-      if (line != '')
-        line += ' \u2190 ';
-      if (link.length > 3 && line.length + link.length > 65) {
-        result += '$line\n';
-        line = '         ';
-      }
-      line += link;
-    }
-    result += line;
-    return result;
+    return chain.join(' \u2190 ');
   }
 
   /// A short, textual description of this element.
@@ -2637,8 +2625,8 @@ abstract class Element implements BuildContext {
     if (children.length > 0) {
       Element last = children.removeLast();
       for (Element child in children)
-        result += '${child.toStringDeep("$prefixOtherLines \u251C", "$prefixOtherLines \u2502")}';
-      result += '${last.toStringDeep("$prefixOtherLines \u2514", "$prefixOtherLines  ")}';
+        result += '${child.toStringDeep("$prefixOtherLines\u251C", "$prefixOtherLines\u2502")}';
+      result += '${last.toStringDeep("$prefixOtherLines\u2514", "$prefixOtherLines ")}';
     }
     return result;
   }