Additional test cases on Integer#chr regarding invalid codepoints.
Additional test cases on Integer#chr regarding invalid codepoints.

Additional tests have been written to ensure RangeError is raised on
a selection of invalid codepoints from UTF-8 and UTF-16.

digitalextremist/rubinius,kachick/rubinius,sferik/rubinius,Wirachmat/rubinius,jemc/rubinius,sferik/rubinius,mlarraz/rubinius,pH14/rubinius,Azizou/rubinius,mlarraz/rubinius,digitalextremist/rubinius,ruipserra/rubinius,benlovell/rubinius,heftig/rubinius,Wirachmat/rubinius,dblock/rubinius,pH14/rubinius,pH14/rubinius,digitalextremist/rubinius,jsyeo/rubinius,jemc/rubinius,ruipserra/rubinius,ngpestelos/rubinius,ngpestelos/rubinius,dblock/rubinius,Wirachmat/rubinius,Azizou/rubinius,benlovell/rubinius,heftig/rubinius,pH14/rubinius,sferik/rubinius,kachick/rubinius,dblock/rubinius,heftig/rubinius,ngpestelos/rubinius,benlovell/rubinius,jsyeo/rubinius,kachick/rubinius,jsyeo/rubinius,dblock/rubinius,jemc/rubinius,digitalextremist/rubinius,Azizou/rubinius,dblock/rubinius,Wirachmat/rubinius,jemc/rubinius,Wirachmat/rubinius,benlovell/rubinius,kachick/rubinius,pH14/rubinius,kachick/rubinius,ngpestelos/rubinius,pH14/rubinius,ruipserra/rubinius,heftig/rubinius,jemc/rubinius,jemc/rubinius,kachick/rubinius,ngpestelos/rubinius,jemc/rubinius,digitalextremist/rubinius,Wirachmat/rubinius,dblock/rubinius,mlarraz/rubinius,sferik/rubinius,heftig/rubinius,dblock/rubinius,digitalextremist/rubinius,sferik/rubinius,mlarraz/rubinius,Azizou/rubinius,Azizou/rubinius,ruipserra/rubinius,jsyeo/rubinius,benlovell/rubinius,ruipserra/rubinius,benlovell/rubinius,pH14/rubinius,heftig/rubinius,Wirachmat/rubinius,kachick/rubinius,mlarraz/rubinius,kachick/rubinius,ruipserra/rubinius,Azizou/rubinius,jsyeo/rubinius,mlarraz/rubinius,ruipserra/rubinius,heftig/rubinius,sferik/rubinius,jsyeo/rubinius,jsyeo/rubinius,benlovell/rubinius,Azizou/rubinius,sferik/rubinius,mlarraz/rubinius,digitalextremist/rubinius,ngpestelos/rubinius,ngpestelos/rubinius