[py] Don't override browser options with desired capabilities by default in WebKitGTK (#6814)
[py] Don't override browser options with desired capabilities by default in WebKitGTK (#6814)

When desired_capabilities parameter is omitted in WebKitGTK driver, the
default capabilities are used. If options are also passed they are
updated from desired capabilities, overriding the passed options. The
desired_capabalities parameter should default to None instead.
Ardesco/selenium,joshmgrant/selenium,Dude-X/selenium,HtmlUnit/selenium,titusfortner/selenium,chrisblock/selenium,asashour/selenium,SeleniumHQ/selenium,HtmlUnit/selenium,lmtierney/selenium,lmtierney/selenium,Dude-X/selenium,lmtierney/selenium,chrisblock/selenium,Ardesco/selenium,oddui/selenium,asashour/selenium,asolntsev/selenium,twalpole/selenium,HtmlUnit/selenium,Dude-X/selenium,twalpole/selenium,HtmlUnit/selenium,twalpole/selenium,chrisblock/selenium,Ardesco/selenium,HtmlUnit/selenium,titusfortner/selenium,titusfortner/selenium,joshbruning/selenium,joshmgrant/selenium,oddui/selenium,twalpole/selenium,asashour/selenium,HtmlUnit/selenium,Dude-X/selenium,SeleniumHQ/selenium,asashour/selenium,joshbruning/selenium,joshmgrant/selenium,Ardesco/selenium,asolntsev/selenium,joshmgrant/selenium,asolntsev/selenium,valfirst/selenium,asolntsev/selenium,Dude-X/selenium,HtmlUnit/selenium,asolntsev/selenium,joshmgrant/selenium,SeleniumHQ/selenium,valfirst/selenium,SeleniumHQ/selenium,titusfortner/selenium,titusfortner/selenium,valfirst/selenium,titusfortner/selenium,asolntsev/selenium,SeleniumHQ/selenium,asolntsev/selenium,Dude-X/selenium,valfirst/selenium,twalpole/selenium,oddui/selenium,valfirst/selenium,twalpole/selenium,joshbruning/selenium,Ardesco/selenium,chrisblock/selenium,joshmgrant/selenium,valfirst/selenium,valfirst/selenium,joshbruning/selenium,SeleniumHQ/selenium,SeleniumHQ/selenium,Ardesco/selenium,asolntsev/selenium,valfirst/selenium,asashour/selenium,Dude-X/selenium,oddui/selenium,oddui/selenium,asashour/selenium,asolntsev/selenium,Ardesco/selenium,lmtierney/selenium,oddui/selenium,chrisblock/selenium,lmtierney/selenium,lmtierney/selenium,chrisblock/selenium,joshbruning/selenium,joshmgrant/selenium,Dude-X/selenium,joshmgrant/selenium,chrisblock/selenium,joshbruning/selenium,joshmgrant/selenium,twalpole/selenium,lmtierney/selenium,valfirst/selenium,titusfortner/selenium,joshmgrant/selenium,SeleniumHQ/selenium,titusfortner/selenium,HtmlUnit/selenium,lmtierney/selenium,oddui/selenium,titusfortner/selenium,HtmlUnit/selenium,titusfortner/selenium,SeleniumHQ/selenium,joshbruning/selenium,Ardesco/selenium,chrisblock/selenium,joshmgrant/selenium,oddui/selenium,oddui/selenium,valfirst/selenium,twalpole/selenium,HtmlUnit/selenium,lmtierney/selenium,valfirst/selenium,asashour/selenium,SeleniumHQ/selenium,joshbruning/selenium,twalpole/selenium,asashour/selenium,asashour/selenium,joshbruning/selenium,chrisblock/selenium,titusfortner/selenium,Ardesco/selenium,Dude-X/selenium,SeleniumHQ/selenium