Removed unnecessary string concatenations

runtime/observatory/lib/src/elements/isolate_view.dart

 // Copyright (c) 2013, 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 isolate_view_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/src/elements/curly_block.dart';
@@ skipping 358 matching lines @@
       ..children = [
         new SpanElement()..text = '${t.id} ',
         new CurlyBlockElement(queue: _r.queue)
           ..content = [
             new DivElement()
               ..classes = ['indent']
               ..text = 'kind ${t.kindString}',
             new DivElement()
               ..classes = ['indent']
               ..title = '${t.zoneHighWatermark}B'
-              ..text = 'zone capacity high watermark ' +
+              ..text = 'zone capacity high watermark '
                   '${Utils.formatSize(t.zoneHighWatermark)}',
             new DivElement()
               ..classes = ['indent']
               ..title = '${t.zoneCapacity}B'
               ..text = 'current zone capacity ' +

[rmacnak, 2017/06/14 16:18:17]

another one

                   '${Utils.formatSize(t.zoneCapacity)}',
           ]
       ];
   }
 
   Future _loadExtraData() async {
     _function = null;
     _rootScript = null;
     final frame = M.topFrame(_isolate.pauseEvent);
     if (frame != null) {
       _function = await _functions.get(_isolate, frame.function.id);
     }
     if (_isolate.rootLibrary != null) {
       final rootLibrary =
           await _libraries.get(_isolate, _isolate.rootLibrary.id);
       _rootScript = rootLibrary.rootScript;
     }
     _r.dirty();
   }
 }