performance - Why is looping through an Array so much faster than JavaScript's native `indexOf`?

Question

Why is looping through an Array so much faster than JavaScript's native indexOf? Is there an error or something that I'm not accounting for? I expected native implementations would be faster.

                For Loop        While Loop      indexOf
Chrome 10.0     50,948,997      111,272,979     12,807,549
Firefox 3.6     9,308,421       62,184,430      2,089,243
Opera 11.10     11,756,258      49,118,462      2,335,347   

http://jsben.ch/#/xm2BV

Answer 1

5 years from then, lot of changes happened in browsers. Now, indexOf performance has increased and is definitely better than any other custom alternative.

Chrome Version 49.0.2623.87 (64-bit)