MDL-56423 stylelint: ignore custom.css files

The files have non-standard css syntax and with stylelint 7.4.1
it can no longer cope with it.

.stylelintignore

@@ -1,5 +1,7 @@
 # Generated by "grunt ignorefiles"
 theme/bootstrapbase/style/
+theme/clean/style/custom.css
+theme/more/style/custom.css
 node_modules/
 vendor/
 auth/cas/CAS/

Gruntfile.js

@@ -221,7 +221,12 @@ module.exports = function(grunt) {
       var eslintIgnores = ['# Generated by "grunt ignorefiles"', '*/**/yui/src/*/meta/', '*/**/build/'].concat(thirdPartyPaths);
       grunt.file.write('.eslintignore', eslintIgnores.join('\n'));
       // Generate .stylelintignore.
-      var stylelintIgnores = ['# Generated by "grunt ignorefiles"', 'theme/bootstrapbase/style/'].concat(thirdPartyPaths);
+      var stylelintIgnores = [
+          '# Generated by "grunt ignorefiles"',
+          'theme/bootstrapbase/style/',
+          'theme/clean/style/custom.css',
+          'theme/more/style/custom.css'
+      ].concat(thirdPartyPaths);
       grunt.file.write('.stylelintignore', stylelintIgnores.join('\n'));
     };
 

theme/clean/style/custom.css

@@ -37,4 +37,4 @@ img.small-logo {
 
 /* Custom CSS Settings
 -------------------------*/
-[[setting:customcss]] /* stylelint-disable-line */
+[[setting:customcss]]

theme/more/style/custom.css

@@ -37,4 +37,4 @@ img.small-logo {
 
 /* Custom CSS Settings
 -------------------------*/
-[[setting:customcss]] /* stylelint-disable-line */
+[[setting:customcss]]