Regression, [SHELL32] shlexec.cpp, "iexplore" can not be called from RunDlg, because ShellExecCmdLine() rejects it to pass

Reproduction steps

• install Gecko during 2nd stage setup
• use the RunDlg from startmenu, which passes its parameters into [SHELL32] shlexec.cpp ShellExecCmdLine()
• type "iexplore" without the quotes

Expected result
Windows XP SP3 runs C:\Program files\iexplore.exe although it is not in the path variable

Observed result
On ros it displays a messagebox about the file not being found. That messagebox is generated by ShellExecCmdLine()
0.4.15-dev-1174-gde8d156_fails.webm
0.4.15-dev-1174-gde8d156_fails.log

It is a regression because it did still work in ReactOS 0.4.7rls0.
ReactOS_0_4_7_rls0_succeeds.webm