Attempt to fix StringIndexOutOfBoundsException

Failure with this Markdown:

*   a list item

    *** aside
    a comment
    ***

Change-Id: I661e08dc0c332ecbb20d72cafc94f830ab7b172b

gitiles-servlet/src/main/java/com/google/gitiles/doc/BlockNoteExtension.java

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/doc/BlockNoteExtension.java b/gitiles-servlet/src/main/java/com/google/gitiles/doc/BlockNoteExtension.java
index 4a37eee..7c18d60 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/doc/BlockNoteExtension.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/doc/BlockNoteExtension.java
@@ -105,7 +105,7 @@
         return BlockStart.none();
       }
 
-      String style = text.subSequence(4, line.length()).toString().trim();
+      String style = text.subSequence(4, text.length()).toString().trim();
       if (!VALID_STYLES.contains(style)) {
         return BlockStart.none();
       }