Any non-special \k is OK.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/scanner/Scanner.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/scanner/Scanner.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/scanner/Scanner.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/scanner/Scanner.java
index 0d73d52dd5ae68b0e2b8b13935c6405bcce05348..aaa1b707f7862989488dbaa3453a082abd815c2d 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/scanner/Scanner.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/scanner/Scanner.java
@@ -951,28 +951,18 @@ public class Scanner {
         if (next == -1) {
           break;
         }
-        boolean missingCharacter = false;
         if (next == '\r') {
-          missingCharacter = true;
           next = reader.advance();
           if (next == '\n') {
             next = reader.advance();
           }
           recordStartOfLine();
         } else if (next == '\n') {
-          missingCharacter = true;
           recordStartOfLine();
           next = reader.advance();
         } else {
           next = reader.advance();
         }
-        if (missingCharacter) {
-          errorListener.onError(new AnalysisError(
-              getSource(),
-              reader.getOffset() - 1,
-              1,
-              ScannerErrorCode.CHARACTER_EXPECTED_AFTER_SLASH));
-        }
       } else if (next == '\r') {
         next = reader.advance();
         if (next == '\n') {