Fix warning work arounded in 12787002.

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

Index: compiler/java/com/google/dart/compiler/type/TypeAnalyzer.java
diff --git a/compiler/java/com/google/dart/compiler/type/TypeAnalyzer.java b/compiler/java/com/google/dart/compiler/type/TypeAnalyzer.java
index d1c574178b393744a2e8c87cc17a9ec138fb1434..e00de43994b7b82c54ce661b2db8b2a279a71b68 100644
--- a/compiler/java/com/google/dart/compiler/type/TypeAnalyzer.java
+++ b/compiler/java/com/google/dart/compiler/type/TypeAnalyzer.java
@@ -1298,7 +1298,7 @@ public class TypeAnalyzer implements DartCompilationPhase {
         for (int i = 0; i < arguments.size(); i++) {
           Type t = bounds.get(i);
           Type s = arguments.get(i);
-          if (!types.isAssignable(t, s)) {
+          if (!types.isSubtype(s, t)) {
             onError(diagnosticNodes.get(i),
                 TypeErrorCode.TYPE_NOT_ASSIGNMENT_COMPATIBLE, s, t);
           }