8029844: Enhance argument validation

Summary: make defensive copy of a varargs array
Reviewed-by: mchung, twisti, ahgross

src/share/classes/java/lang/invoke/MethodHandles.java

@@ -2070,6 +2070,7 @@ assert((int)twice.invokeExact(21) == 42);
      */
     public static
     MethodHandle permuteArguments(MethodHandle target, MethodType newType, int... reorder) {
+        reorder = reorder.clone();
         checkReorder(reorder, newType, target.type());
         return target.permuteArguments(newType, reorder);
     }
@@ -2264,6 +2265,7 @@ assertEquals("yz", (String) d0.invokeExact(123, "x", "y", "z"));
             throw newIllegalArgumentException("no argument type to remove");
         ArrayList<Class<?>> ptypes = new ArrayList<>(oldType.parameterList());
         ptypes.addAll(pos, valueTypes);
+        if (ptypes.size() != inargs)  throw newIllegalArgumentException("valueTypes");
         MethodType newType = MethodType.methodType(oldType.returnType(), ptypes);
         return target.dropArguments(newType, pos, dropped);
     }