Use limited JavaStringBuilder implementation instead of Dart StringBuffer.

pkg/analyzer-experimental/lib/src/generated/source.dart

 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.source;
 
 import 'dart:uri';
 import 'java_core.dart';
 
 /**
  * Instances of the class {@code SourceFactory} resolve possibly relative URI's against an existing{@link Source source}.
@@ skipping 347 matching lines @@
     if (offset >= other.end) {
       return false;
     }
     return true;
   }
   /**
    * @return <code>true</code> if this {@link SourceRange} starts in <code>otherRange</code>.
    */
   bool startsIn(SourceRange otherRange) => otherRange.contains(_offset);
   String toString() {
-    StringBuffer builder = new StringBuffer();
-    builder.write("[offset=");
-    builder.write(_offset);
-    builder.write(", length=");
-    builder.write(_length);
-    builder.write("]");
+    JavaStringBuilder builder = new JavaStringBuilder();
+    builder.append("[offset=");
+    builder.append(_offset);
+    builder.append(", length=");
+    builder.append(_length);
+    builder.append("]");
     return builder.toString();
   }
 }
 /**
  * The interface {@code SourceContainer} is used by clients to define a collection of sources
  * <p>
  * Source containers are not used within analysis engine, but can be used by clients to group
  * sources for the purposes of accessing composite dependency information. For example, the Eclipse
  * client uses source containers to represent Eclipse projects, which allows it to easily compute
  * project-level dependencies.
@@ skipping 103 matching lines @@
    * @param contents the new contents of the source
    */
   void setContents(Source source, String contents) {
     if (contents == null) {
       _contentMap.remove(source);
     } else {
       _contentMap[source] = contents;
     }
   }
 }