update elements and fix some bugs

lib/src/prism/components/prism-less.js

 /* FIXME :
  :extend() is not handled specifically : its highlighting is buggy.
  Mixin usage must be inside a ruleset to be highlighted.
  At-rules (e.g. import) containing interpolations are buggy.
  Detached rulesets are highlighted as at-rules.
  A comment before a mixin usage prevents the latter to be properly highlighted.
  */
 
 Prism.languages.less = Prism.languages.extend('css', {
         'comment': [
@@ skipping 11 matching lines @@
         },
         // selectors and mixins are considered the same
         'selector': {
                 pattern: /(?:@\{[\w-]+\}|[^{};\s@])(?:@\{[\w-]+\}|\([^{}]*\)|[^{};@])*?(?=\s*\{)/,
                 inside: {
                         // mixin parameters
                         'variable': /@+[\w-]+/
                 }
         },
 
-        'property': /(\b|\B)(?:@\{[\w-]+\}|[\w-])+(?:\+_?)?(?=\s*:)/i,
+        'property': /(?:@\{[\w-]+\}|[\w-])+(?:\+_?)?(?=\s*:)/i,
         'punctuation': /[{}();:,]/,
         'operator': /[+\-*\/]/
 });
 
 // Invert function and punctuation positions
 Prism.languages.insertBefore('less', 'punctuation', {
         'function': Prism.languages.less.function
 });
 
 Prism.languages.insertBefore('less', 'property', {
         'variable': [
                 // Variable declaration (the colon must be consumed!)
                 {
                         pattern: /@[\w-]+\s*:/,
                         inside: {
                                 "punctuation": /:/
                         }
                 },
 
                 // Variable usage
                 /@@?[\w-]+/
         ],
         'mixin-usage': {
                 pattern: /([{;]\s*)[.#](?!\d)[\w-]+.*?(?=[(;])/,
                 lookbehind: true,
                 alias: 'function'
         }
 });