float_literal.vert.html should not test about missing gl_Position.
Add two extra tests to cover that:
empty_main.vert.html
gl_position_unset.vert.html
Update 00_test_list.txt
Merge pull request #361 from zhenyao/fix

Test about unwritten gl_Position in vertex shaders.
Fixed link to IDL; also updated link to latest and current spec in editor's draft.
Merge pull request #362 from kenrussell/idl-link

Fixed link to IDL; also updated link to latest and current spec in edito...