More skylark function cleanups

--
MOS_MIGRATED_REVID=91407816
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java
index dce075a..fb9e2fd 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/BuiltinFunction.java
@@ -246,11 +246,11 @@
           String msg = String.format(
               "fun %s(%s), param %s, enforcedType: %s (%s); parameterType: %s",
               getName(), signature, signature.getSignature().getNames().get(i),
-              enforcedType, enforcedType.getClass(), parameterType);
+              enforcedType, enforcedType.getType(), parameterType);
           if (enforcedType instanceof SkylarkType.Simple
               || enforcedType instanceof SkylarkFunctionType) {
             Preconditions.checkArgument(
-                enforcedType == SkylarkType.of(parameterType), msg);
+                enforcedType.getType() == parameterType, msg);
             // No need to enforce Simple types on the Skylark side, the JVM will do it for us.
             enforcedArgumentTypes.set(i, null);
           } else if (enforcedType instanceof SkylarkType.Combination) {