removed unused 'prefix' line from status files

tools/testing/dart/status_file_parser.dart

Index: tools/testing/dart/status_file_parser.dart
diff --git a/tools/testing/dart/status_file_parser.dart b/tools/testing/dart/status_file_parser.dart
index 89cd4c4eb97c77e40e65f0654927b830c1babe55..76b1d69ae38e0eece8bf587069819c6d55f67479 100644
--- a/tools/testing/dart/status_file_parser.dart
+++ b/tools/testing/dart/status_file_parser.dart
@@ -19,7 +19,6 @@ final OK = "ok";
 final RegExp StripComment = const RegExp("^[^#]*");
 final RegExp HeaderPattern = const RegExp(@"^\[([^\]]+)\]");
 final RegExp RulePattern = const RegExp(@"\s*([^: ]*)\s*:(.*)");
-final RegExp PrefixPattern = const RegExp(@"^\s*prefix\s+([\w\_\.\-\/]+)\s*$");
 
 // TODO(whesse): Implement configuration_info library that contains data
 // structures for test configuration, including Section.
@@ -64,7 +63,6 @@ void ReadConfigurationInto(path, sections, onDone) {
 
   Section current = new Section.always();
   sections.add(current);
-  String prefix = "";
 
   lines.onLine = () {
     String line;
@@ -96,12 +94,6 @@ void ReadConfigurationInto(path, sections, onDone) {
         continue;
       }
 
-      match = PrefixPattern.firstMatch(line);
-      if (match != null) {
-        prefix = match[1];
-        continue;
-      }
-
       print("unmatched line: $line");
     }
   };