Fix warning work arounded in 12787002.

compiler/java/com/google/dart/compiler/type/Types.java

Index: compiler/java/com/google/dart/compiler/type/Types.java
diff --git a/compiler/java/com/google/dart/compiler/type/Types.java b/compiler/java/com/google/dart/compiler/type/Types.java
index 44f401e282e6f357ddcd93d9b9dbb679aa290622..8e83daf9a3bd62d52752853f8f0741ede31b9d9e 100644
--- a/compiler/java/com/google/dart/compiler/type/Types.java
+++ b/compiler/java/com/google/dart/compiler/type/Types.java
@@ -344,6 +344,21 @@ public class Types {
         return isSubtype(tBound, sv);
       }
     }
+    // May be concrete InterfaceType.
+    if (t.getKind() == TypeKind.INTERFACE) {
+      InterfaceType ti = (InterfaceType) t;
+      Type sBound = sv.getTypeVariableElement().getBound();
+      if (sBound == null) {
+        return true;
+      }
+      // Prevent cycle.
+      if (sBound.equals(sv)) {
+        return false;
+      }
+      if (sBound.getKind() == TypeKind.INTERFACE) {
+        return isSubtype(ti, sBound);
+      }
+    }
     // no
     return false;
   }