Fix property-name interpolation

This commit makes sure to correctly apply propety-name meta scope, even if
property name starts with interpolation.

Prepares for sublimehq/Packages#3785

Requires ST4149+

Syntaxes/CSS (Liquid).sublime-syntax

@@ -11,6 +11,9 @@ file_extensions:
   - css.liquid
   - liquid.css
 
+variables:
+  ident_start: (?:{{nmstart}}|{{)
+
 contexts:
 
   prototype:
@@ -20,3 +23,18 @@ contexts:
   string-content:
     - meta_prepend: true
     - include: scope:source.liquid#interpolations
+
+  at-supports-group-body:
+    - meta_prepend: true
+    - meta_include_prototype: false
+    - include: scope:source.liquid#liquid-tags
+
+  property-lists:
+    - match: \{(?!{)
+      scope: punctuation.section.block.begin.css
+      push: property-list-body
+
+  property-list-body:
+    - meta_prepend: true
+    - meta_include_prototype: false
+    - include: scope:source.liquid#liquid-tags

tests/syntax_test_liquid.liquid.html

@@ -679,10 +679,11 @@
 |             ^^^^ constant.language.boolean.liquid
 |                  ^^ punctuation.section.embedded.end.liquid
 ;       {{prop}}: {{value}};
-|       ^^^^^^^^ meta.interpolation.liquid
+|       ^^^^^^^^ meta.property-name.css support.type.property-name.css meta.interpolation.liquid
 |                 ^^^^^^^^^ meta.property-value.css meta.interpolation.liquid
 ;       font-{{family}}: "{{font}}";
-|            ^^^^^^^^^^ source.css.embedded.html meta.property-list.css meta.block.css meta.interpolation.liquid
+|       ^^^^^^^^^^^^^^^ support.type.property-name.css
+|            ^^^^^^^^^^ meta.property-list.css meta.block.css meta.property-name.css meta.interpolation.liquid
 |            ^^ punctuation.section.interpolation.begin.liquid
 |              ^^^^^^ variable.other.liquid
 |                    ^^ punctuation.section.interpolation.end.liquid