buffer: fix inspect throw if slice length too long

All the Buffer#{ascii,hex,etc.}Slice() methods are intentionally strict
to alert if a Buffer instance was attempting to be accessed out of
bounds. Buffer#toString() is the more user friendly way of accessing the
data, and will coerce values to their min/max on overflow.

lib/buffer.js

@@ -239,7 +239,7 @@ Buffer.prototype.inspect = function inspect() {
   var str = '';
   var max = exports.INSPECT_MAX_BYTES;
   if (this.length > 0) {
-    str = this.hexSlice(0, max).match(/.{2}/g).join(' ');
+    str = this.toString('hex', 0, max).match(/.{2}/g).join(' ');
     if (this.length > max)
       str += ' ... ';
   }