fix for frexp dataflow analysis

Bug: skia:
Change-Id: Ic20bedadfbf37fd78ce03872ece2d9552307cfcd
Reviewed-on: https://skia-review.googlesource.com/117243
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Chris Dalton <csmartdalton@google.com>
3 files changed