Fix line name interpolation

Line names are scoped as unquoted strings, thus need to clear string-scope.
Hence prepend `less-string-interpolations` even though interpolation is already
handled by `identifier-content`.

Author: deathaxe

Syntaxes/Less.sublime-syntax

@@ -347,7 +347,7 @@ contexts:
     - match: '{{lang_range_begin}}'
       push: language-range-content
 
-  line-names-content:
+  line-name-content:
     - meta_prepend: true
     - include: less-string-interpolations
 

tests/syntax_test_less.less

@@ -815,6 +815,16 @@ custom-@{element}-selector {}
 //                      ^^^^^^^^ 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
+
+    grid: [@{line}name, line@{name}, li@{ne}name];
+//         ^^^^^^^ meta.string.css meta.interpolation.less - string
+//                ^^^^ meta.string.css string.unquoted.line-name.css
+//                      ^^^^ meta.string.css string.unquoted.line-name.css
+//                          ^^^^^^^ meta.string.css meta.interpolation.less - string
+//                                   ^^ meta.string.css string.unquoted.line-name.css
+//                                     ^^^^^ meta.string.css meta.interpolation.less - string
+//                                          ^^^^ meta.string.css string.unquoted.line-name.css
+
 }
 
 //=============================================================================