This fixes an IsCanonical() DCHECK failure triggered by calling
CanonicalCookie::Create for a non-cookieable URL.
This change also adds unit test coverage for cross-origin cookie
behavior with sub-resource requests (iframe, XHR, Fetch).
- CefURLRequest::Create is no longer supported in the renderer process
(see https://crbug.com/891872). Use CefFrame::CreateURLRequest instead.
- Mac platform definitions have been changed from `MACOSX` to `MAC`
(see https://crbug.com/1105907) and related CMake macro names have
been updated. The old `OS_MACOSX` define is still set in code and CMake
for backwards compatibility.
- Linux ARM build is currently broken (see https://crbug.com/1123214).
To reduce text execution time and flakyness this change also
introduces a global test server that is initialized when needed
and torn down after all tests have completed.
