Fix int64 overflow in SkClampRange::init()

BUG=skia:5915,skia:6219

Change-Id: Ic849bf9dc90e623fc1d6269cd245a2e3eca05d1d
Reviewed-on: https://skia-review.googlesource.com/8290
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed