Initial support for mixins in dartc.

compiler/java/com/google/dart/compiler/resolver/Resolver.java

Index: compiler/java/com/google/dart/compiler/resolver/Resolver.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/Resolver.java b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
index 6a9c2b352558b975891781db5ab9ef569b0ce876..f40cb666b9aa9fa87c9f44224695d4e92c79cd51 100644
--- a/compiler/java/com/google/dart/compiler/resolver/Resolver.java
+++ b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
@@ -22,6 +22,7 @@ import com.google.dart.compiler.ast.DartBreakStatement;
 import com.google.dart.compiler.ast.DartCase;
 import com.google.dart.compiler.ast.DartCatchBlock;
 import com.google.dart.compiler.ast.DartClass;
+import com.google.dart.compiler.ast.DartClassTypeAlias;
 import com.google.dart.compiler.ast.DartComment;
 import com.google.dart.compiler.ast.DartCommentNewName;
 import com.google.dart.compiler.ast.DartCommentRefName;
@@ -358,6 +359,21 @@ public class Resolver {
       }
       return null;
     }
+    
+    @Override
+    public Element visitClassTypeAlias(DartClassTypeAlias cls) {
+      ClassNodeElement classElement = cls.getElement();
+      try {
+        classElement.getAllSupertypes();
+      } catch (CyclicDeclarationException e) {
+        HasSourceInfo errorTarget = e.getElement();
+        if (errorTarget == null) {
+          errorTarget = cls;
+        }
+        onError(errorTarget, ResolverErrorCode.CYCLIC_CLASS, e.getElement().getName());
+      }
+      return classElement;
+    }
 
     @Override
     public Element visitClass(DartClass cls) {