add classification for type aliases

src/services/services.ts

@@ -1291,6 +1291,7 @@ module ts {
         public static interfaceName = "interface name";
         public static moduleName = "module name";
         public static typeParameterName = "type parameter name";
+        public static typeAlias = "type alias name";
     }
 
     enum MatchKind {
@@ -4946,6 +4947,9 @@ module ts {
                 else if (flags & SymbolFlags.Enum) {
                     return ClassificationTypeNames.enumName;
                 }
+                else if (flags & SymbolFlags.TypeAlias) {
+                    return ClassificationTypeNames.typeAlias;
+                }
                 else if (meaningAtPosition & SemanticMeaning.Type) {
                     if (flags & SymbolFlags.Interface) {
                         return ClassificationTypeNames.interfaceName;

tests/cases/fourslash/fourslash.ts

@@ -639,6 +639,10 @@ module FourSlashInterface {
             return getClassification("typeParameterName", text, position);
         }
 
+        export function typeAlias(text: string, position?: number): { classificationType: string; text: string; textSpan?: TextSpan } {
+            return getClassification("typeAlias", text, position);
+        }
+
         function getClassification(type: string, text: string, position?: number) {
             return {
                 classificationType: type,

tests/cases/fourslash/semanticClassificatonTypeAlias.ts

@@ -0,0 +1,15 @@
+/// <reference path="fourslash.ts"/>
+
+////type /*0*/Alias = number
+////var x: /*1*/Alias;
+////var y = </*2*/Alias>{};
+////function f(x: /*3*/Alias): /*4*/Alias { return undefined; }
+
+var c = classification;
+verify.semanticClassificationsAre(
+    c.typeAlias("Alias", test.marker("0").position),
+    c.typeAlias("Alias", test.marker("1").position),
+    c.typeAlias("Alias", test.marker("2").position),
+    c.typeAlias("Alias", test.marker("3").position),
+    c.typeAlias("Alias", test.marker("4").position)
+    );