Fix for function type assignable check.

editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/internal/type/FunctionTypeImplTest.java

Index: editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/internal/type/FunctionTypeImplTest.java
diff --git a/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/internal/type/FunctionTypeImplTest.java b/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/internal/type/FunctionTypeImplTest.java
index 60b37ee842b255894256100a8e4a50339a011817..19b42bfd8b853adb249c0c3e8d706bc8dc364699 100644
--- a/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/internal/type/FunctionTypeImplTest.java
+++ b/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/internal/type/FunctionTypeImplTest.java
@@ -86,6 +86,18 @@ public class FunctionTypeImplTest extends EngineTestCase {
     type.hashCode();
   }
 
+  public void test_isAssignableTo_normalAndPositionalArgs() {
+    // ([a]) -> void <: (a) -> void
+    ClassElement a = classElement("A");
+    FunctionType t = functionElement("t", null, new ClassElement[] {a}).getType();
+    FunctionType s = functionElement("s", new ClassElement[] {a}).getType();
+    assertTrue(t.isSubtypeOf(s));
+    assertFalse(s.isSubtypeOf(t));
+    // assignable iff subtype
+    assertTrue(t.isAssignableTo(s));
+    assertFalse(s.isAssignableTo(t));
+  }
+
   public void test_isSubtypeOf_baseCase_classFunction() {
     // () -> void <: Function
     ClassElementImpl functionElement = classElement("Function");