[css mode] Support lineComment option, enable it for LESS, SCSS

mode/css/css.js

@@ -28,6 +28,7 @@ CodeMirror.defineMode("css", function(config, parserConfig) {
       colorKeywords = parserConfig.colorKeywords || {},
       valueKeywords = parserConfig.valueKeywords || {},
       allowNested = parserConfig.allowNested,
+      lineComment = parserConfig.lineComment,
       supportsAtComponent = parserConfig.supportsAtComponent === true;
 
   var type, override;
@@ -407,6 +408,7 @@ CodeMirror.defineMode("css", function(config, parserConfig) {
     electricChars: "}",
     blockCommentStart: "/*",
     blockCommentEnd: "*/",
+    lineComment: lineComment,
     fold: "brace"
   };
 });
@@ -730,6 +732,7 @@ CodeMirror.defineMode("css", function(config, parserConfig) {
     valueKeywords: valueKeywords,
     fontProperties: fontProperties,
     allowNested: true,
+    lineComment: "//",
     tokenHooks: {
       "/": function(stream, state) {
         if (stream.eat("/")) {
@@ -772,6 +775,7 @@ CodeMirror.defineMode("css", function(config, parserConfig) {
     valueKeywords: valueKeywords,
     fontProperties: fontProperties,
     allowNested: true,
+    lineComment: "//",
     tokenHooks: {
       "/": function(stream, state) {
         if (stream.eat("/")) {