The current lookup for the Firefox executable on Windows exhibits
two problems: it relies on architecture specific paths (such
as Wow6432Node), and it skips looking at HKEY_CURRENT_USER for
applications that are not installed system-wide.
The first problem manifests when using the 32-bit version of
geckodriver on a 64-bit host system, or when the Firefox executable
has a different architecture than geckodriver.
The second issue is that mozrunner entirely ignores user-specific
installations of Firefox.
This patch looks at the two following keys, which seems to more
reliably be able to tell us the location of the Firefox executable,
irregardless of the process executable's bitness:
When they exist, these should return:
(Default) REG_SZ C:\Program Files (x86)\FirefoxESR\firefox.exe
Path REG_SZ C:\Program Files (x86)\FirefoxESR\firefox.exe