Fix parsing of another missed block comment

Fixes sass#1021

constants.cpp

@@ -127,6 +127,10 @@ namespace Sass {
     extern const char map_name[]        = "map";
     extern const char arglist_name[]    = "arglist";
 
+    // some specific constant character classes
+    // they must be static to be useable by lexer
+    extern const char static_ops[]      = "*/%";
+
     // byte order marks
     // (taken from http://en.wikipedia.org/wiki/Byte_order_mark)
     extern const unsigned char utf_8_bom[]      = { 0xEF, 0xBB, 0xBF };

constants.hpp

@@ -130,6 +130,10 @@ namespace Sass {
     extern const char map_name[];
     extern const char arglist_name[];
 
+    // some specific constant character classes
+    // they must be static to be useable by lexer
+    extern const char static_ops[];
+
     // byte order marks
     // (taken from http://en.wikipedia.org/wiki/Byte_order_mark)
     extern const unsigned char utf_8_bom[];

parser.cpp

@@ -1191,29 +1191,24 @@ namespace Sass {
   Expression* Parser::parse_term()
   {
     Expression* fact1 = parse_factor();
-
     // Special case: Ruby sass never tries to modulo if the lhs contains an interpolant
-    if (peek< exactly<'%'> >(position) && fact1->concrete_type() == Expression::STRING) {
+    if (peek_css< exactly<'%'> >(position) && fact1->concrete_type() == Expression::STRING) {
       String_Schema* ss = dynamic_cast<String_Schema*>(fact1);
       if (ss && ss->has_interpolants()) return fact1;
     }
-
-    // if it's a singleton, return it directly; don't wrap it
-    if (!(peek< exactly<'*'> >(position) ||
-          peek< exactly<'/'> >(position) ||
-          peek< exactly<'%'> >(position)))
-    { return fact1; }
-
-    while (lex< block_comment >());
+    // parse more ops and factors
     vector<Expression*> operands;
     vector<Binary_Expression::Type> operators;
-    while (lex< exactly<'*'> >() || lex< exactly<'/'> >() || lex< exactly<'%'> >()) {
+    while (lex_css< class_char< static_ops > >()) {
       if      (lexed.to_string() == "*") operators.push_back(Binary_Expression::MUL);
       else if (lexed.to_string() == "/") operators.push_back(Binary_Expression::DIV);
-      else                   operators.push_back(Binary_Expression::MOD);
+      else if (lexed.to_string() == "%") operators.push_back(Binary_Expression::DIV);
+      else throw runtime_error("unknown static op parsed");
       operands.push_back(parse_factor());
     }
-
+    // maybe return as a singleton
+    if (operands.empty()) return fact1;
+    // fold operands into a binary expression
     return fold_operands(fact1, operands, operators);
   }
 
@@ -1275,7 +1270,7 @@ namespace Sass {
 
   Expression* Parser::parse_value()
   {
-    while (lex< block_comment >());
+    lex< css_comments >();
     if (lex< uri_prefix >()) {
       Arguments* args = new (ctx.mem) Arguments(pstate);
       Function_Call* result = new (ctx.mem) Function_Call(pstate, "url", args);