Fix unquoted url interpolation

Author: deathaxe

Syntaxes/Less.sublime-syntax

@@ -25,6 +25,7 @@ variables:
   tag_name_begin: (?=[[:alpha:]]|@+{)
 
   lang_range_begin: (?={{ident_start}}|\*)
+  unquoted_url_begin: (?={{ident_start}}|/)
 
   # Less variables
 
@@ -354,7 +355,10 @@ contexts:
     - meta_prepend: true
     - include: less-string-interpolations
 
+###[ CSS URL STRINGS ]#########################################################
+
   quoted-url:
+    # does not yet exist in CSS but is not unlikely
     - match: \"
       scope:
         meta.string.css string.quoted.double.css
@@ -366,6 +370,15 @@ contexts:
         punctuation.definition.string.begin.css
       set: single-quoted-url-body
 
+  unquoted-urls:
+    # replace CSS context to add interpolation support
+    - match: '{{unquoted_url_begin}}'
+      push: unquoted-url-body
+
+  unquoted-url-body:
+    - meta_prepend: true
+    - include: less-string-interpolations
+
 ###[ CSS PROTOTYPES ]##########################################################
 
   terminator-pop:

tests/syntax_test_less.less

@@ -806,6 +806,15 @@ custom-@{element}-selector {}
 //             ^^^^^^^^ meta.string.css meta.interpolation.less
 //                     ^ - meta.string - meta.interpolation
 //                      ^^^^^^^^^^^ meta.function-call
+
+    image: url(@{server}/assets/@{image}.png);
+//        ^ meta.property-value.css - meta.function-call
+//         ^^^ meta.property-value.css meta.function-call.identifier.css
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ meta.property-value.css meta.function-call.arguments.css meta.group.css
+//             ^^^^^^^^^ meta.path.url.css meta.string.css meta.interpolation.less - string
+//                      ^^^^^^^^ meta.path.url.css meta.string.css string.unquoted.css
+//                              ^^^^^^^^ meta.path.url.css meta.string.css meta.interpolation.less - string
+//                                      ^^^^ meta.path.url.css meta.string.css string.unquoted.css
 }
 
 //=============================================================================