fix: prevent zero length tokens in raw-blocks (#1577)

This comment ensures that the lexer is not stuck on zero-length tokens, in raw-blocks like {{{{a}}}} {{{{/a}}}}

src/handlebars.l

@@ -63,7 +63,7 @@ ID    [^\s!"#%-,\.\/;->@\[-\^`\{-~]+/{LOOKAHEAD}
                                     return 'END_RAW_BLOCK';
                                   }
                                  }
-<raw>[^\x00]*?/("{{{{")          { return 'CONTENT'; }
+<raw>[^\x00]+/("{{{{")          { return 'CONTENT'; }
 
 <com>[\s\S]*?"--"{RIGHT_STRIP}?"}}" {
   this.popState();

src/handlebars.yy

@@ -39,7 +39,7 @@ content
   };
 
 rawBlock
-  : openRawBlock content+ END_RAW_BLOCK -> yy.prepareRawBlock($1, $2, $3, @$)
+  : openRawBlock content* END_RAW_BLOCK -> yy.prepareRawBlock($1, $2, $3, @$)
   ;
 
 openRawBlock