BlameDetail.soy: remove unused regionIdx alias

Change-Id: I25e900bc99a3d0d76a54f512a367edb39bb89db8
diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/templates/BlameDetail.soy b/gitiles-servlet/src/main/resources/com/google/gitiles/templates/BlameDetail.soy
index 9b3b76d..2bf0a30 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/templates/BlameDetail.soy
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/templates/BlameDetail.soy
@@ -44,7 +44,6 @@
   {call .blobHeader data="$data" /}
 
   <table id="blame">
-    {let $regionIdx: 0 /}
     {foreach $line in $data.lines}
       {let $i: index($line) /}
       {let $region: $regions[index($line)] /}