[PATCH] Active tab looks ugly (inherits system color scheme only partially)

I use Tor Browser 4.5-alpha-1 on KDE, my gtk+ theme is oxygen-gtk. As I found from looking into sources of Tor Browser, when it renders site content, it uses some stand-ins for native colors to avoid browser fingerprinting. And these stand-ins should not be used when rendering browser interface - the variable useStandinsForNativeColors in layout/style/nsRuleNode.cpp:890 (function SetColor):

  bool useStandinsForNativeColors = aPresContext && !aPresContext->IsChrome();

But this condition is not enough to fully distinguish browser interface from site content. Look at the attached screenshot to see that left and right corners of active tab are lighter than middle of the tab - this is because the middle renders with system colors, and corners render with stand-ins while stand-ins should be really disabled for them.

I discovered that two files correspond for corners of the tab: chrome://browser/skin/tabbrowser/tab-selected-start.svg and chrome://browser/skin/tabbrowser/tab-selected-end.svg, and IsChrome() function returns false for this files, so stand-ins are used when they shouldn't.

I think that the attached patch should be used in order to handle correctly those two svg files.

Trac:
Username: gentoo_root