Makes an error message friendlier when trying to invoke

compiler/java/com/google/dart/compiler/resolver/TypeErrorCode.java

Index: compiler/java/com/google/dart/compiler/resolver/TypeErrorCode.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/TypeErrorCode.java b/compiler/java/com/google/dart/compiler/resolver/TypeErrorCode.java
index 0d3267fff2332061dab4043fddae48e94482be0e..416d34e736786e402b7c122e359d6ed1468b674f 100644
--- a/compiler/java/com/google/dart/compiler/resolver/TypeErrorCode.java
+++ b/compiler/java/com/google/dart/compiler/resolver/TypeErrorCode.java
@@ -37,6 +37,7 @@ public enum TypeErrorCode implements ErrorCode {
   SUPERTYPE_HAS_FIELD("%s is a field in %s"),
   SUPERTYPE_HAS_METHOD("%s is a method in %s"),
   TYPE_NOT_ASSIGNMENT_COMPATIBLE("%s is not assignable to %s"),
+  USE_ASSIGNMENT_ON_SETTER("Use assignment to set field \"%s\" in %s"),
   VOID("expression does not yield a value"),
   WRONG_NUMBER_OF_TYPE_ARGUMENTS("%s: wrong number of type arguments");
   private final ErrorSeverity severity;
@@ -57,14 +58,17 @@ public enum TypeErrorCode implements ErrorCode {
     this.message = message;
   }
 
+  @Override
   public String getMessage() {
     return message;
   }
 
+  @Override
   public ErrorSeverity getErrorSeverity() {
     return severity;
   }
 
+  @Override
   public SubSystem getSubSystem() {
     return SubSystem.STATIC_TYPE;
   }