Fix 'data:,'-uri attachement treatment

Change-Id: Icf92033fe24103271ba52a2dda65ea198fca25b2
diff --git a/dev/js/src/match/attachement.js b/dev/js/src/match/attachement.js
index 4548703..7b6cb94 100644
--- a/dev/js/src/match/attachement.js
+++ b/dev/js/src/match/attachement.js
@@ -10,7 +10,7 @@
  * @author Nils Diewald
  */
 define(function () {
-  const uriRE = new RegExp("^data: *([^;,]+?(?: *; *[^,;]+?)*) *, *(.+)$");
+  const uriRE = new RegExp("^data: *([^;,]*?(?: *; *[^,;]+?)*) *, *(.+)$");
   const mapRE = new RegExp("^ *([^=]+?) *= *(.+?) *$");
 
   return {