WD6 issues: Minor typo in JSTF table

[Bob Hallissy]

The current working draft still contains this error:

On 2013-09-09 1:59 PM, Behdad Esfahbod wrote:
> In the JstfPriority table, the comments for ExtensionEnableGPOS and
> ExtensionDisableGPOS say GSUB while they should say GPOS.
>