Fix \t being replaced with a space (‽)

WTF? interpreting escape sequences and then replacing tabs with spaces?

someone fucked up badly in c028bbd1cd286909da91d8bc24a74fbac0eabf2a, [look here](https://github.com/zcbenz/d3-browserify/blob/master/d3.js#L2020): an important tab is replaced with a space. why the hell would any editor do that anywhere else but in leading whitespace? (assuming it was a code editor, no person)

but the real mistake is that at some point of the import, the `"\t"` in the original code gets unescaped and replaced with a real tab. that must not happen.