Fix max call stack issue (#99)

* Fix issue with RangeError called on concat.apply()

When calling the flatten function with a sufficiently large array it
will throw: RangeError: Maximum call stack size exceeded

This was found when processing very large xml documents and using a //
selector in select().

This is due to the maximum argument length limit in javascript/node.
Calling apply() with a sufficiently large array will throw a RangeError.
See https://bugs.webkit.org/show_bug.cgi?id=80797 for details.

Chunk the array into chunks that are smaller than the maximum argument
list size using `slice()` and call `concat.apply()` on each chunk so
that we never get the range error.

* Argument limit issue - remove use of prototypeSlice and unnecessary use of min()

Co-authored-by: Mike Noseworthy <mike.noseworthy@gmail.com>

xpath.js

@@ -167,8 +167,19 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
 
     var prototypeConcat = Array.prototype.concat;
 
+    // .apply() fails above a certain number of arguments - https://github.com/goto100/xpath/pull/98
+    var MAX_ARGUMENT_LENGTH = 32767;
+
     function flatten(arr) {
-        return prototypeConcat.apply([], arr);
+        var result = [];
+
+        for (var start = 0; start < arr.length; start += MAX_ARGUMENT_LENGTH) {
+            var chunk = arr.slice(start, start + MAX_ARGUMENT_LENGTH);
+
+            result = prototypeConcat.apply(result, chunk);
+        }
+
+        return result;
     }
 
     function assign(target, varArgs) { // .length of function is 2