classloading bugfixes and stack trace work

classpath/java/lang/Throwable.java

@@ -2,6 +2,26 @@ package java.lang;
 
 public class Throwable {
   private String message;
-  private Object trace;
+  private StackTraceElement[] trace;
   private Throwable cause;
+
+  public Throwable(String message, Throwable cause) {
+    this.message = message;
+    this.trace = trace(1);
+    this.cause = cause;
+  }
+
+  public Throwable(String message) {
+    this(message, null);
+  }
+
+  public Throwable(Throwable cause) {
+    this(null, cause);
+  }
+
+  public Throwable() {
+    this(null, null);
+  }
+
+  private static native StackTraceElement[] trace(int skipCount);
 }