Change getattr() behavior so 3-arg form doesn't fail when field is a method

RELNOTES: getattr()'s 3-arg form no longer raises an error when the retrieved field is a built-in method.

--
MOS_MIGRATED_REVID=137390666
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java b/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java
index 98552bb..b70e1f6 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java
@@ -478,7 +478,7 @@
             + "a method of that name exists";
     new SkylarkTest()
         .testIfExactError(msg, "getattr('a string', 'count')")
-        .testIfExactError(msg, "getattr('a string', 'count', 'unused default')");
+        .testStatement("getattr('a string', 'count', 'default')", "default");
   }
 
   @Test