Replace ${name} with $name where possible.

pkg/analyzer/lib/src/services/runtime/coverage/models.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.
 
 /// A library with code coverage models.
 library runtime.coverage.model;
 
 import 'dart:collection' show SplayTreeMap;
 
 import 'package:analyzer/src/generated/source.dart' show Source, SourceRange;
@@ skipping 71 matching lines @@
       sink.writeln('$prefix  "children": {');
       children.fold(null, (prev, child) {
         if (prev != null) sink.writeln(',');
         return child..write(sink, executedIds, '$prefix    ');
       });
       sink.writeln();
       sink.writeln('$prefix  }');
     }
     // Print source and line ranges.
     if (children.isEmpty) {
-      sink.write('${prefix}  "ranges": [');
+      sink.write('$prefix  "ranges": [');
       var rangePrinter = new RangePrinter(unit, sink, executedIds);
       idToRange.forEach(rangePrinter.handle);
       rangePrinter.printRange();
       sink.writeln(']');
     }
     // Close this node.
     sink.write('$prefix}');
   }
 
   UnitInfo get unit => parent.unit;
@@ skipping 56 matching lines @@
       : super(appInfo, null, 'unit', path) {
     lineOffsets = getLineOffsets(content);
   }
 
   UnitInfo get unit => this;
 
   int getLine(int offset) {
     return binarySearch(lineOffsets, (x) => x >= offset);
   }
 }