if open class is not referenced from own final classes, so, define it inplace

src/com/google/dart/compiler/backend/js/ast/ChameleonJsExpression.java

@@ -6,6 +6,13 @@ import com.google.dart.compiler.common.SourceInfo;
 public class ChameleonJsExpression implements JsExpression {
     private JsExpression expression;
 
+    public ChameleonJsExpression(JsExpression initialExpression) {
+        expression = initialExpression;
+    }
+
+    public ChameleonJsExpression() {
+    }
+
     public void resolve(JsExpression expression) {
         this.expression = expression;
     }