Clang was complaining that we were casting a char* to a wchar_t*.

BUG=angle:707

Change-Id: I063165e9add4e9b57d131181da30c05e5abbc1c2
Reviewed-on: https://chromium-review.googlesource.com/209618Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>