Remove use of minimumValueForLength in HTMLAreaElement::getRegion

While the 'coords' attribute on HTMLAreaElement is stored as a
Vector<Length>, the Lengths will all be of the type 'Fixed'. This means
that the only effect of minimumValueForLength() will be to round-trip
through LayoutUnit - resulting in a clamp to the allowed range of
LayoutUnit. Replace the uses of minimumValueForLength() with a new
function (clampCoordinate) that only does this clamping.

No functional changes.

BUG=578114

Review URL: https://codereview.chromium.org/1619793002

Cr-Commit-Position: refs/heads/master@{#371184}
1 file changed