JS: Do not parse the initial ! or = as part of the template expression

Author: asgerf

javascript/extractor/src/com/semmle/js/extractor/TemplateEngines.java

@@ -8,7 +8,7 @@
 
 public class TemplateEngines {
   private static final String MUSTACHE_TAG_TRIPLE = "\\{\\{\\{[~]?(.*?)[~]?\\}\\}\\}"; // {{{ x }}}
-  private static final String MUSTACHE_TAG_DOUBLE = "\\{\\{(?!\\{)[~&]?(.*?)[~]?\\}\\}"; // {{ x }}}
+  private static final String MUSTACHE_TAG_DOUBLE = "\\{\\{(?!\\{)[~&!=]?(.*?)[~]?\\}\\}"; // {{ x }}}
   private static final String MUSTACHE_TAG_PERCENT = "\\{%(?!>)(.*?)%\\}"; // {% x %}
   private static final String EJS_TAG = "<%(?![%<>}])[-=]?(.*?)[_-]?%>"; // <% x %>