Fall back to the |defaultEncoding| when no valid "post" table is found in TrueType fonts (bug 1050040)

Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1050040.

With this patch the file is completely readable, but given that the font is broken enough to be rejected by OTS the rendering differs slightly from Adobe Reader.

*Note:* the PDF file is sufficiently broken that even Adobe Reader complains about the font, *and* also about another more general issue.

src/core/fonts.js

@@ -3697,6 +3697,9 @@ var Font = (function FontClosure() {
           default:
             warn('Unknown/unsupported post table version ' + version);
             valid = false;
+            if (properties.defaultEncoding) {
+              glyphNames = properties.defaultEncoding;
+            }
             break;
         }
         properties.glyphNames = glyphNames;