Don't ignore .txt file extension

So far, gitiles treats .txt files are if they had no extension. It
passes "null" to java-prettify which results in a default langugage
resulting in all the text turning green after an "unclosed" ' or "
character. Using txt for "*.txt" fixes the issue.

Test: Test: bazelisk build //:gitiles && tools/run_dev.sh
Bug: NA
Change-Id: I9bb4f0a2914822ba376d1028e69a9682588d008b

java/com/google/gitiles/BlobSoyData.java

diff --git a/java/com/google/gitiles/BlobSoyData.java b/java/com/google/gitiles/BlobSoyData.java
index 956222f..e898101 100644
--- a/java/com/google/gitiles/BlobSoyData.java
+++ b/java/com/google/gitiles/BlobSoyData.java
@@ -189,9 +189,7 @@
     int slash = path.lastIndexOf('/');
     int dot = path.lastIndexOf('.');
     String ext = ((0 < dot) && (slash < dot)) ? path.substring(dot + 1) : null;
-    if ("txt".equalsIgnoreCase(ext)) {
-      return null;
-    } else if ("mk".equalsIgnoreCase(ext)) {
+    if ("mk".equalsIgnoreCase(ext)) {
       return "sh";
     } else if ("Makefile".equalsIgnoreCase(path)
         || ((0 < slash) && "Makefile".equalsIgnoreCase(path.substring(slash + 1)))) {

modules/java-prettify

diff --git a/modules/java-prettify b/modules/java-prettify
index 54d1c6c..8af621b 160000
--- a/modules/java-prettify
+++ b/modules/java-prettify
@@ -1 +1 @@
-Subproject commit 54d1c6c735a92cad8c67cb4c9fcd1d090605c88e
+Subproject commit 8af621b7b99641eb803caa460009290a47fa3111