Fix WebEngineContext on Windows

AppendSwitchASCII won't accept WChars, it would need WideToASCII
conversion. But on OS_WIN AppendSwitchASCII method only wraps
parameters for AppendSwitchNative with ASCIIToWide.
Doing ASCIIToWide(WideToASCII()) not seems to be a useful idea,
so we should call directly AppendSwitchNative on Windows.
See chromium/base/command_line.cc.

Change-Id: I9733993840ddaef2dbb3176135977c39a967e381
Reviewed-by: Andras Becsi <andras.becsi@digia.com>
Fix RenderWidgetHostViewQt::GetCompositingSurface() on Windows

gfx::GLSurfaceHandle needs reinterpret_cast for the first parameter
to match an overload.

Change-Id: I4b89c38b9694ab649e1e623049573675c926a4a7
Reviewed-by: Michael Bruning <michael.bruning@digia.com>
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>