Fix error handling for formatting and update the spec

pkg/analysis_server/lib/src/protocol.dart

Index: pkg/analysis_server/lib/src/protocol.dart
diff --git a/pkg/analysis_server/lib/src/protocol.dart b/pkg/analysis_server/lib/src/protocol.dart
index bdc8608d20026257da80eee5e4b16e527e8df598..a0854aa871f19f723bc0e74fd904672cd03edf53 100644
--- a/pkg/analysis_server/lib/src/protocol.dart
+++ b/pkg/analysis_server/lib/src/protocol.dart
@@ -690,14 +690,22 @@ class Response {
       : _result = result;
 
   /**
-   * Initialize a newly created instance to represent the
-   * FORMAT_INVALID_FILE error condition.
+   * Initialize a newly created instance to represent the FORMAT_INVALID_FILE
+   * error condition.
    */
   Response.formatInvalidFile(Request request) : this(request.id,
           error: new RequestError(RequestErrorCode.FORMAT_INVALID_FILE,
               'Error during `edit.format`: invalid file.'));
 
   /**
+   * Initialize a newly created instance to represent the FORMAT_WITH_ERROR
+   * error condition.
+   */
+  Response.formatWithErrors(Request request) : this(request.id,
+          error: new RequestError(RequestErrorCode.FORMAT_WITH_ERRORS,
+              'Error during `edit.format`: source contains syntax errors.'));
+
+  /**
    * Initialize a newly created instance based upon the given JSON data
    */
   factory Response.fromJson(Map<String, Object> json) {