Revert "Add basic implementation of IsModifiableClass"

Built on top of a failing change.

This reverts commit b4e51ebfa23a1cb175a6c317ac4a69228709e78f.

Change-Id: I7f4dbe22271a9c04e518bceabba12c95cad3c6f7
diff --git a/test/912-classes/src/Main.java b/test/912-classes/src/Main.java
index e627d42..69e5a4c 100644
--- a/test/912-classes/src/Main.java
+++ b/test/912-classes/src/Main.java
@@ -107,9 +107,7 @@
   private static void testClassType(Class<?> c) throws Exception {
     boolean isInterface = isInterface(c);
     boolean isArray = isArrayClass(c);
-    boolean isModifiable = isModifiableClass(c);
-    System.out.println(c.getName() + " interface=" + isInterface + " array=" + isArray +
-        " modifiable=" + isModifiable);
+    System.out.println(c.getName() + " interface=" + isInterface + " array=" + isArray);
   }
 
   private static void testClassFields(Class<?> c) throws Exception {
@@ -151,7 +149,6 @@
     }
   }
 
-  private static native boolean isModifiableClass(Class<?> c);
   private static native String[] getClassSignature(Class<?> c);
 
   private static native boolean isInterface(Class<?> c);