clarified javadoc

src/org/objectweb/asm/tree/analysis/Interpreter.java

@@ -49,6 +49,10 @@ public interface Interpreter {
     /**
      * Creates a new value that represents the given type.
      * 
+     * Called for method parameters (including <code>this</code>),
+     * exception handler variable and with <code>null</code> type 
+     * for variables reserved by long and double types.
+     * 
      * @param type a primitive or reference type, or <tt>null</tt> to
      *        represent an uninitialized value.
      * @return a value that represents the given type. The size of the returned