Nintendo has released the 3DS Browser source code. The source code can be downloaded from the link below.Be aware that this does not come with warranty of any kind. Here is a quote from the Nintendo website:

The Internet Browser includes open source software licensed under the terms of the GNU library General Public License 2.0 or GNU Lesser General Public license 2.1 (collectively "the OSS Licenses"). In compliance with the OSS Licenses, we are making the source code of the open source software available to you.

*Please note that the open source software is without warranty of any kind.

For more information on LGPL please see the e-manual of the Internet Browser for Nintendo 3DS

3DS Browser Open Source