Bug swiftshader:99
Bug chromium:820461

Change-Id: I2232c27d57aedff03293b37607f97ead56c056c9
Reviewed-on: https://swiftshader-review.googlesource.com/17808Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>