Allow more characters in unquoted property values

corpus/declarations.txt

@@ -95,3 +95,19 @@ a {
     (block
       (declaration (property_name) (string_value))
       (declaration (property_name) (string_value)))))
+
+============================
+URLs
+============================
+
+a {
+  b: http://something-else?foo=bar;
+}
+
+---
+
+(stylesheet
+  (rule_set
+    (selectors (tag_name))
+    (block
+      (declaration (property_name) (plain_value)))))

corpus/selectors.txt

@@ -67,8 +67,8 @@ a[b] {}
 
 (stylesheet
   (rule_set (selectors (attribute_selector (attribute_name))) (block))
-  (rule_set (selectors (attribute_selector (attribute_name) (keyword_value))) (block))
-  (rule_set (selectors (attribute_selector (attribute_name) (keyword_value))) (block))
+  (rule_set (selectors (attribute_selector (attribute_name) (plain_value))) (block))
+  (rule_set (selectors (attribute_selector (attribute_name) (plain_value))) (block))
   (rule_set (selectors (attribute_selector (tag_name) (attribute_name))) (block)))
 
 =========================

corpus/statements.txt

@@ -33,11 +33,11 @@ Media statements
       (binary_query
         (keyword_query)
         (feature_query (feature_name) (integer_value (unit))))
-      (feature_query (feature_name) (keyword_value)))
+      (feature_query (feature_name) (plain_value)))
     (block))
   (media_statement
     (feature_query (feature_name) (integer_value (unit)))
-    (binary_query (keyword_query) (feature_query (feature_name) (keyword_value)))
+    (binary_query (keyword_query) (feature_query (feature_name) (plain_value)))
     (block))
   (media_statement
     (binary_query (negated_query (keyword_query)) (parenthesized_query (keyword_query)))

grammar.js

@@ -180,7 +180,8 @@ module.exports = grammar({
     // Property Values
 
     _value: $ => choice(
-      alias($.identifier, $.keyword_value),
+      alias($.identifier, $.plain_value),
+      $.plain_value,
       $.color_value,
       $.integer_value,
       $.float_value,
@@ -238,6 +239,8 @@ module.exports = grammar({
 
     identifier: $ => /[a-zA-Z-_][a-zA-Z0-9-_]*/,
 
+    plain_value: $ => /[a-zA-Z-_][^;()\[\]\s]*/,
+
     at_keyword: $ => /@[a-zA-Z-_]+/,
 
     comment: $ => token(choice(

src/grammar.json

@@ -768,7 +768,11 @@
             "name": "identifier"
           },
           "named": true,
-          "value": "keyword_value"
+          "value": "plain_value"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "plain_value"
         },
         {
           "type": "SYMBOL",
@@ -1134,6 +1138,10 @@
       "type": "PATTERN",
       "value": "[a-zA-Z-_][a-zA-Z0-9-_]*"
     },
+    "plain_value": {
+      "type": "PATTERN",
+      "value": "[a-zA-Z-_][^;()\\[\\]\\s]*"
+    },
     "at_keyword": {
       "type": "PATTERN",
       "value": "@[a-zA-Z-_]+"