Fix regression caused by earlier bitwise and optimisation. 1 & undefined != 1.

Fix regression caused by earlier bitwise and optimisation.  1 & undefined != 1.

Reviewed by Maciej.

The implementation of JSImmediate::areBothImmediateNumbers relies on
(JSImmediate::getTag(immediate1) & JSImmediate::getTag(immediate2)) having
a unique result when both immediate values are numbers.

The regression was due to UndefinedType & NumberType returning NumberType (3 & 1).
By swapping the value of NumberType and UndefinedType this ceases to be a problem.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@27630 268f45cc-cd09-0410-ab3c-d52691b4dbfc