Move alternateImpl detection into MethodInfo constructor.
Remove additional "if (!method.key)" check.
Merge pull request #414 from mcav/alternate-2

Move alternateImpl detection into MethodInfo constructor.
Merge branch 'master' of https://github.com/andreasgal/j2me.js into jitjit

Conflicts:
	classinfo.js
No need to recalc methodInfo key in VM.compile after #414