JS: Optimize base58 decoding.
JS: Optimize base58 decoding.

ripple/ripple-lib,wilsonianb/ripple-lib,wilsonianb/ripple-lib,ripple/ripple-lib,darkdarkdragon/ripple-lib,darkdarkdragon/ripple-lib,wilsonianb/ripple-lib,ripple/ripple-lib,darkdarkdragon/ripple-lib,ripple/ripple-lib