WebKitGtk doesn't respect the font specified in html files, it always use the same font for rendering Arabic regardless of the specified font, even if it has Arabic glyphs. More ever, choosing a font that doesn't have Latin glyphs causes the English text to be rendered as white spaces or boxes.
Created attachment 18546 [details]
Comment on attachment 18546 [details]
><HTML style="font-family: Dejavu Sans; font-size: 50px;"><HEAD>
><META content="text/html; charset=utf-8" http-equiv="Content-Type"/></HEAD><BODY>أبجد هوز حطي كلمن
>The Quich Brown Fox
Created attachment 18547 [details]
Screenshot of the testcase in GtkLauncher
Created attachment 18548 [details]
The same testcase in Epiphany
Created attachment 18550 [details]
Screenshot with "Lohit Punjabi" font
This font doesn't have Latin glyphs
Created attachment 18551 [details]
Correcting the font name, sorry
Thanks for the detailed bug description.
The lack of integration between the WebKit Pango text renderer and the font selection system is the cause of the Arabic text always using a default font. The simple fix for this depends on the patch in #15229 landing.
The block carets for western text may be related to an issue in the simple text path, bug #16792.
Fixed in r36309 for the "FreeType" backend I believe. Please re-open if the issue persists.