Can I somehow get jQuery size smaller if I only target to WebKit?

When been looking ZeptoJs and started to assume if I would be able to remove all IE&Firefox specific stuff I would get very small jQuery file.

Is there a tool or some code generator that removes all browser/version specific code so I can target to specific browser and get jquery file size smaller?

I am writing application to iPhone and I would like to use jQue开发者_开发知识库ry but only with webkit-engine. Something like Zeptojs does but I want to stay on jQuery.