[css mode] Make @import highlighting consistent with other contexts

Closes #3475

Author: marijnh

mode/css/css.js

@@ -164,9 +164,11 @@ CodeMirror.defineMode("css", function(config, parserConfig) {
       return popContext(state);
     } else if (supportsAtComponent && /@component/.test(type)) {
       return pushContext(state, stream, "atComponentBlock");
-    } else if (/@(media|supports|(-moz-)?document)/.test(type)) {
+    } else if (/^@(-moz-)?document$/.test(type)) {
+      return pushContext(state, stream, "documentTypes");
+    } else if (/^@(media|supports|(-moz-)?document|import)$/.test(type)) {
       return pushContext(state, stream, "atBlock");
-    } else if (/@(font-face|counter-style)/.test(type)) {
+    } else if (/^@(font-face|counter-style)/.test(type)) {
       state.stateArg = type;
       return "restricted_atBlock_before";
     } else if (/^@(-(moz|ms|o|webkit)-)?keyframes$/.test(type)) {
@@ -259,17 +261,24 @@ CodeMirror.defineMode("css", function(config, parserConfig) {
     return pass(type, stream, state);
   };
 
+  states.documentTypes = function(type, stream, state) {
+    if (type == "word" && documentTypes.hasOwnProperty(stream.current())) {
+      override = "tag";
+      return state.context.type;
+    } else {
+      return states.atBlock(type, stream, state);
+    }
+  };
+
   states.atBlock = function(type, stream, state) {
     if (type == "(") return pushContext(state, stream, "atBlock_parens");
-    if (type == "}") return popAndPass(type, stream, state);
+    if (type == "}" || type == ";") return popAndPass(type, stream, state);
     if (type == "{") return popContext(state) && pushContext(state, stream, allowNested ? "block" : "top");
 
     if (type == "word") {
       var word = stream.current().toLowerCase();
       if (word == "only" || word == "not" || word == "and" || word == "or")
         override = "keyword";
-      else if (documentTypes.hasOwnProperty(word))
-        override = "tag";
       else if (mediaTypes.hasOwnProperty(word))
         override = "attribute";
       else if (mediaFeatures.hasOwnProperty(word))

mode/css/test.js

@@ -120,7 +120,7 @@
      "}");
 
   MT("empty_url",
-     "[def @import] [tag url]() [tag screen];");
+     "[def @import] [atom url]() [attribute screen];");
 
   MT("parens",
      "[qualifier .foo] {",