Make lines and columns one-based in SourceLocation.

pkg/compiler/lib/src/io/position_information.dart

Index: pkg/compiler/lib/src/io/position_information.dart
diff --git a/pkg/compiler/lib/src/io/position_information.dart b/pkg/compiler/lib/src/io/position_information.dart
index 0400e61535cb427281ccdc37dd81b9043bc5d15f..d6889d71dc0492dc32bee91d7014af1f73d621c5 100644
--- a/pkg/compiler/lib/src/io/position_information.dart
+++ b/pkg/compiler/lib/src/io/position_information.dart
@@ -69,12 +69,12 @@ class PositionSourceInformation extends SourceInformation {
     sb.write('$uriText:');
     // Use 1-based line/column info to match usual dart tool output.
     if (startPosition != null) {
-      sb.write('[${startPosition.line + 1},'
-          '${startPosition.column + 1}]');
+      sb.write('[${startPosition.line},'
+          '${startPosition.column}]');
     }
     if (closingPosition != null) {
-      sb.write('-[${closingPosition.line + 1},'
-          '${closingPosition.column + 1}]');
+      sb.write('-[${closingPosition.line},'
+          '${closingPosition.column}]');
     }
     return sb.toString();
   }