fix cubic clip in y
Follow on to https://codereview.chromium.org/1299243002/
Clip using a geometric solution if the algebraic solution
fails in Y as well as in X.
If the root finder discovers real roots that are sufficiently
far apart, the root in the range of 0..1 can contain so much
error that it is computed to be slightly smaller than 0 or
larger than 1.
In this case, binary search the mono curve for the actual
answer.
R=reed@google.com
Review URL: https://codereview.chromium.org/1303873003
2 files changed