Expose the exceptions info in the diagnostics page.

pkg/analysis_server/lib/src/status/pages.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:intl/intl.dart';
 
 /// Contains a collection of Pages.
@@ skipping 131 matching lines @@
   void p(String text, {String style, bool raw: false, String classes}) {
     String c = classes == null ? '' : ' class="$classes"';
 
     if (style != null) {
       buf.writeln('<p$c style="$style">${raw ? text : escape(text)}</p>');
     } else {
       buf.writeln('<p$c>${raw ? text : escape(text)}</p>');
     }
   }
 
+  void pre(void gen(), {String classes}) {
+    if (classes != null) {
+      buf.write('<pre class="$classes">');
+    } else {
+      buf.write('<pre>');
+    }
+    gen();
+    buf.writeln('</pre>');
+  }
+
   void blankslate(String str) {
     div(() => buf.writeln(str), classes: 'blankslate');
   }
 
   bool isCurrentPage(String pathToTest) => path == pathToTest;
 }
 
 String escape(String text) => text == null ? '' : HTML_ESCAPE.convert(text);
 
 final NumberFormat numberFormat = new NumberFormat.decimalPattern();
 
 String printInteger(int value) => numberFormat.format(value);
 
 String printMilliseconds(num value) => '${numberFormat.format(value)} ms';
 
 String printPercentage(num value) => '${(value * 100).toStringAsFixed(1)}%';