adding a kind of detection of em-size when loading font from cff file 

FontForge sets the a default em-size of 1000 when loading type 1 fonts from a cff file. For at least one specific font, which initial em-size was 2048, this caused a mismatch between em-size and glyph size ; which then caused fonts to be stretched when exported through pdf2htmlEX. 

I joined a basic test with the extracted font file, and also the pdf page where I encountered the problem.