diff --git a/pkg/front_end/lib/src/fasta/scanner/error_token.dart b/pkg/front_end/lib/src/fasta/scanner/error_token.dart
index e848c70..40c54b6 100644
--- a/pkg/front_end/lib/src/fasta/scanner/error_token.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/error_token.dart
@@ -164,6 +164,8 @@
 
   int get charCount => endOffset - charOffset;
 
+  int get length => charCount;
+
   Message get assertionMessage =>
       templateUnterminatedString.withArguments(start, closeQuoteFor(start));
 }
diff --git a/pkg/front_end/testcases/rasta/bad_interpolation.dart.outline.expect b/pkg/front_end/testcases/rasta/bad_interpolation.dart.outline.expect
index b9d119d..f08449b 100644
--- a/pkg/front_end/testcases/rasta/bad_interpolation.dart.outline.expect
+++ b/pkg/front_end/testcases/rasta/bad_interpolation.dart.outline.expect
@@ -2,7 +2,7 @@
 //
 // pkg/front_end/testcases/rasta/bad_interpolation.dart:6:13: Error: String starting with " must end with ".
 //   print(" $x.);
-//             ^
+//             ^^^
 //
 // pkg/front_end/testcases/rasta/bad_interpolation.dart:6:8: Error: Can't find ')' to match '('.
 //   print(" $x.);
diff --git a/pkg/front_end/testcases/regress/issue_29976.dart.direct.expect b/pkg/front_end/testcases/regress/issue_29976.dart.direct.expect
index 5724ac3..2ed84b8 100644
--- a/pkg/front_end/testcases/regress/issue_29976.dart.direct.expect
+++ b/pkg/front_end/testcases/regress/issue_29976.dart.direct.expect
@@ -7,7 +7,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 //
@@ -44,7 +44,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -52,7 +52,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29976.dart.direct.transformed.expect b/pkg/front_end/testcases/regress/issue_29976.dart.direct.transformed.expect
index 1e80af7..adcec4e 100644
--- a/pkg/front_end/testcases/regress/issue_29976.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_29976.dart.direct.transformed.expect
@@ -7,7 +7,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29976.dart.outline.expect b/pkg/front_end/testcases/regress/issue_29976.dart.outline.expect
index 7f8efff..b796c52 100644
--- a/pkg/front_end/testcases/regress/issue_29976.dart.outline.expect
+++ b/pkg/front_end/testcases/regress/issue_29976.dart.outline.expect
@@ -7,7 +7,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 
diff --git a/pkg/front_end/testcases/regress/issue_29976.dart.strong.expect b/pkg/front_end/testcases/regress/issue_29976.dart.strong.expect
index 032bd88..72e0f84 100644
--- a/pkg/front_end/testcases/regress/issue_29976.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_29976.dart.strong.expect
@@ -7,7 +7,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 //
@@ -44,7 +44,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -52,7 +52,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29976.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_29976.dart.strong.transformed.expect
index 7b89520..8c288dc 100644
--- a/pkg/front_end/testcases/regress/issue_29976.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_29976.dart.strong.transformed.expect
@@ -7,7 +7,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:15: Error: String starting with ' must end with '.
 //     "x${x*"'"é'}x
-//               ^
+//               ^^^
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:7: Error: Can't find '}' to match '${'.
 //     "x${x*"'"é'}x
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:9:5: Error: String starting with " must end with ".
 //     "x${x*"'"é'}x
-//     ^
+//     ^^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29976.dart:12:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29982.dart.direct.expect b/pkg/front_end/testcases/regress/issue_29982.dart.direct.expect
index 409dd9a..3828528 100644
--- a/pkg/front_end/testcases/regress/issue_29982.dart.direct.expect
+++ b/pkg/front_end/testcases/regress/issue_29982.dart.direct.expect
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 //
@@ -52,7 +52,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29982.dart.direct.transformed.expect b/pkg/front_end/testcases/regress/issue_29982.dart.direct.transformed.expect
index cf55a97..11a5695 100644
--- a/pkg/front_end/testcases/regress/issue_29982.dart.direct.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_29982.dart.direct.transformed.expect
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29982.dart.outline.expect b/pkg/front_end/testcases/regress/issue_29982.dart.outline.expect
index 60e4f5b..28ba42c 100644
--- a/pkg/front_end/testcases/regress/issue_29982.dart.outline.expect
+++ b/pkg/front_end/testcases/regress/issue_29982.dart.outline.expect
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 
diff --git a/pkg/front_end/testcases/regress/issue_29982.dart.strong.expect b/pkg/front_end/testcases/regress/issue_29982.dart.strong.expect
index 96c2b57..cbd79b7 100644
--- a/pkg/front_end/testcases/regress/issue_29982.dart.strong.expect
+++ b/pkg/front_end/testcases/regress/issue_29982.dart.strong.expect
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 //
@@ -52,7 +52,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 //
diff --git a/pkg/front_end/testcases/regress/issue_29982.dart.strong.transformed.expect b/pkg/front_end/testcases/regress/issue_29982.dart.strong.transformed.expect
index 9a1c7cd..e9542e0 100644
--- a/pkg/front_end/testcases/regress/issue_29982.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/regress/issue_29982.dart.strong.transformed.expect
@@ -15,7 +15,7 @@
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:7:11: Error: String starting with ' must end with '.
 //   print('${eh[éh']}');
-//           ^
+//           ^^^^^^^^^^^^^...
 //
 // pkg/front_end/testcases/regress/issue_29982.dart:9:1: Error: Expected a declaration, but got ''.
 //