Use limited JavaStringBuilder implementation instead of Dart StringBuffer.

editor/util/plugins/com.google.dart.java2dart/resources/java_core.dart

Index: editor/util/plugins/com.google.dart.java2dart/resources/java_core.dart
diff --git a/editor/util/plugins/com.google.dart.java2dart/resources/java_core.dart b/editor/util/plugins/com.google.dart.java2dart/resources/java_core.dart
index a450fbd85de638cc6afdb9fe190f37f7403ca222..7119161c4ca76e929f4ddb4570189b6fdac821bd 100644
--- a/editor/util/plugins/com.google.dart.java2dart/resources/java_core.dart
+++ b/editor/util/plugins/com.google.dart.java2dart/resources/java_core.dart
@@ -390,3 +390,22 @@ void javaMapPutAll(Map target, Map source) {
 bool javaStringEqualsIgnoreCase(String a, String b) {
   return a.toLowerCase() == b.toLowerCase();
 }
+
+class JavaStringBuilder {
+  StringBuffer sb = new StringBuffer();
+  String toString() => sb.toString();
+  void append(x) {
+    sb.write(x);
+  }
+  void appendChar(int c) {
+    sb.writeCharCode(c);
+  }
+  int get length => sb.length;
+  void set length(int len) {
+    var s = sb.toString().substring(0, len);

[floitsch, 2013/03/06 16:52:18]

Note that the Java StringBuilder also accepts a new length that is greater that
the current length. In that case it fills the builder with '\0' characters.

[scheglov, 2013/03/06 17:12:21]

Thank you!
Fixed.

+    sb = new StringBuffer(s);
+  }
+  void clear() {
+    sb = new StringBuffer();
+  }
+}