Comment 9 for bug 86889

The zoom_*() methods are implemented in libgtkhtml2-0, and the gtkhtml libraries does what it's supposed to do, in that HTML rendering is of the correct size.

Thus, the root cause is with the CHM files specifying a small font; they're all tested on windows platforms, where presumably the font-size gets adjusted for, in favour legacy compatibility, so we need to add this 'hack' to be compliant give correct rendering results w.r.t. Microsoft's CHM/help viewer.

Attached patch for fix.