Not an answer, just some clues, perhaps, to the use, "to be noncommittal or inconstant".

Compare:
wiffle-waffle, whiffle-waffle


http://books.google.com/books?id=poJBAQAAIAAJ&pg=PA488&dq=%22wiffle%22&hl=en&sa=X&ei=b-FUVIWTAtbdsATg-YDwDw&ved=0CEQQ6AEwBjgU#v=onepage&q=%22wiffle%22&f=false


The first (*English Dialect Dictionary*, Joseph Wright) gives a definition of *wiffle-waffle* "to whet a scythe", which I understand (perhaps incorrectly?) to involve a back-and-forth motion. Wright finds the attestation on page 141 of *The Dialect And Folk-Lore Of Northamptonshire* by Thomas Sternberg. London. 1851

 *Wiffle* (whiffle) and *waffle* (whaffle, woffle) seem to involve swinging or swaying or moving back and forth (literal 'vacillation'); the word *wiffle-waffle* has among its meanings 'to speak in a meandering manner'. In the American use of 'waffling politicians', they either speak in an evasive manner so as not to be held to an opinion, or they flip-flop and say today the opposite of what they said last week.

The second instance from *Dizionario Delle Lingue Italiana Ed Inglese*, Giuseppe Marco Antonio Baretti, (1839), gives a definition for [*whiffle*][1] : to swing, to sway back and forth (*muoversi ondeggiando...dondolarsi*).  [But this link was mere lagniappe :-) ]


See also *[whiffle-whaffle][2]* : "a person of unsteady, vacillating character" in   
*The Dialect of Craven in the West Riding of the County of York* (1828). 

![snippet including the following terms: whiff, whiffle and whiffle-whaffle][3]


  [1]: http://books.google.it/books?id=nNkFAAAAQAAJ&pg=PT647&dq=%22whiffle%22&hl=en&sa=X&ei=KuJUVNLcB5DasATDhoDQBg&redir_esc=y#v=onepage&q=%22whiffle%22&f=false
  [2]: https://archive.org/stream/dialectcraven00unkngoog#page/n262/mode/2up
  [3]: https://i.sstatic.net/yUV9U.jpg


P.S.
In his *A Glossary of the Cleveland Dialect* (London, 1868) the Reverend J.C. Atkinson defines **waffle** as "to waver or vacillate; to be undecided" and refers to Old Norse *vöflur* (doubt, uncertainty, hesitation).