frog: generalize checking that type args aren't used in static methods

frog/member.dart

Index: frog/member.dart
diff --git a/frog/member.dart b/frog/member.dart
index d93f4aa51a6a9c3c792981202300734c9d2523ee..c6b0c1d0dea7982d35cb6cb8387982b62a35861b 100644
--- a/frog/member.dart
+++ b/frog/member.dart
@@ -24,10 +24,6 @@ class Parameter {
 
     type = method.resolveType(definition.type, false);
 
-    if (method.isStatic && method.typeParameters === null && type.hasTypeParams) {
-      world.error('using type parameter in static context', definition.span);
-    }
-
     if (definition.value != null) {
       // To match VM, detect cases where value was not actually specified in
       // code and don't signal errors.
@@ -1390,6 +1386,16 @@ class MethodMember extends Member {
       library._addMember(this);
     }
   }
+
+  /** Overriden to ensure that type arguments aren't used in static methods. */
+  Type resolveType(TypeReference node, bool typeErrors) {
+    Type t = super.resolveType(node, typeErrors);
+    if (isStatic && t is ParameterType &&
+       (typeParameters === null || !typeParameters.some((p) => p === t))) {
+      world.error('using type parameter in static context.', node.span);
+    }
+    return t;
+  }
 }