[OpenJDK 2D-Dev] RFR: 8198412 : MonospacedGlyphWidthTest.java may fail on Solaris

[Phil Race]

bug: https://bugs.openjdk.java.net/browse/JDK-8198412
webrev: http://cr.openjdk.java.net/~prr/8198412/

Updates the test to make sure we even support ascii as monospaced before
testing the other ranges. Also makes sure the code points it is testing are
supported else the test  may not be valid either.

-phil.